#### Sample records for angle silicon array

1. TIARA: a large solid angle silicon array for direct reaction studies with radioactive beams

Labiche, M; Lemmon, R C; Timis, C N; Orr, N A; Fernandez-Dominguez, B; Chapman, R; Achouri, N L; Amzal, N; Appleton, S; Ashwood, N I; Baldwin, T D; Burns, M; Caballero, L; Cacitti, J; Casadjian, J M; Chartier, M; Curtis, N; Faiz, K; De France, G; Freer, M; Gautier, J M; Gelletly, W; Iltis, G; Lecornu, B; Liang, X; Marry, C; Merrer, Y; Moores, G; Olivier, L; Pain, S D; Pucknell, V F E; Raine, B; Rejmund, M; Rubio, B; Saillant, F; Savajols, H; Sorlin, O; Spohr, K; Theisen, Ch; Voltolini, G; Warner, D D

2009-01-01

A compact, quasi-4pi position sensitive silicon array, TIARA, designed to study direct reactions induced by radioactive beams in inverse kinematics is described here. The Transfer and Inelastic All-angle Reaction Array (TIARA) consists of 8 resistive-strip silicon detectors forming an octagonal barrel around the target and a set of double-sided silicon-strip annular detectors positioned at each end of the barrel. The detector was coupled to the gamma-ray array EXOGAM and the spectrometer VAMOS at the GANIL Laboratory to demonstrate the potential of such an apparatus with radioactive beams. The 14N(d,p)15N reaction, well known in normal kinematics, has been carried out in inverse kinematics for that purpose. The observation of the 15N ground state and excited states at 7.16 and 7.86 MeV is presented here as well as the comparison of the measured proton angular distributions with DWBA calculations. Transferred l-values are in very good agreement with both theoretical calculations and previous experimental resul...

2. Wide angle and broadband antireflection properties for a silicon nanotip array

Huang, Yi-Fan; Jen, Yi-Jun; Chen, Kuei-Hsien; Chen, Li-Chyong

2008-08-01

Biomimetic structures provided important clues for nano-synthesis in pursuit of enhanced performances. Here, we report a wide angle and broadband antireflection is observed on a 6-inch silicon nanotip array (SiNTs) substrate fabricated using a single step electron cyclotron resonance plasma etching technique. This subwavelength structure consists of the SiNTs with apex and bottom diameter of ~5 nm and ~200 nm, respectively, length of ~1600 nm and density of 109/cm2. This aperiodic array of SiNTs with geometry designed in the sub-wavelength level to demonstrate a low hemispherical reflectance of Dobrowolski. This near ideal antireflection property suggests enhanced performances in renewable energy, and electro-optical devices in defense applications.

3. Silicon Heat Pipe Array

Yee, Karl Y.; Ganapathi, Gani B.; Sunada, Eric T.; Bae, Youngsam; Miller, Jennifer R.; Beinsford, Daniel F.

2013-01-01

Improved methods of heat dissipation are required for modern, high-power density electronic systems. As increased functionality is progressively compacted into decreasing volumes, this need will be exacerbated. High-performance chip power is predicted to increase monotonically and rapidly with time. Systems utilizing these chips are currently reliant upon decades of old cooling technology. Heat pipes offer a solution to this problem. Heat pipes are passive, self-contained, two-phase heat dissipation devices. Heat conducted into the device through a wick structure converts the working fluid into a vapor, which then releases the heat via condensation after being transported away from the heat source. Heat pipes have high thermal conductivities, are inexpensive, and have been utilized in previous space missions. However, the cylindrical geometry of commercial heat pipes is a poor fit to the planar geometries of microelectronic assemblies, the copper that commercial heat pipes are typically constructed of is a poor CTE (coefficient of thermal expansion) match to the semiconductor die utilized in these assemblies, and the functionality and reliability of heat pipes in general is strongly dependent on the orientation of the assembly with respect to the gravity vector. What is needed is a planar, semiconductor-based heat pipe array that can be used for cooling of generic MCM (multichip module) assemblies that can also function in all orientations. Such a structure would not only have applications in the cooling of space electronics, but would have commercial applications as well (e.g. cooling of microprocessors and high-power laser diodes). This technology is an improvement over existing heat pipe designs due to the finer porosity of the wick, which enhances capillary pumping pressure, resulting in greater effective thermal conductivity and performance in any orientation with respect to the gravity vector. In addition, it is constructed of silicon, and thus is better

4. OPTIMIZATION OF TILT ANGLE FOR PHOTOVOLTAIC ARRAY

Ashok Kumar; N.S.Thakur,; Rahul Makade,; Maneesh Kumar Shivhar

2011-01-01

The performance of a solar radiation conversion system is affected by its tilt angle with the horizontal plane, thus photovoltaic array need to be tilted at the correct angle to maximize the performance of the System, This paper deals with the determination of optimum tilt angle for solar PV array in order to maximize incident solar irradiance. The model starts by calculating the monthly averaged daily solar irradiation components (direct, diffuse, ground- eflected) absorbed by the solar PV a...

5. The high granularity and large solid angle detection array EXPADES

Highlights: • We realized a detection array for Exotic Radioactive Ion Beams. • High granularity (32 × 32 pixels 2 × 2 mm wide for 8 telescopes). • High solid angle (8 telescopes 64 × 64 mm wide in a cylindrical configuration covering up to 2.6 sr). • We tested each component of the array by both alpha particles and in-beam environment. • We measured the angular distribution for 17O elastic scattering on a 58Ni target. -- Abstract: The EXPADES (EXotic PArticle DEtection System) detector array consists of 16 Double Side Silicon Strip Detectors (DSSSD) with active areas of 64 × 64 mm2, arranged in 8 ΔE (40/50 μm)–E (300 μm) telescopes. All detector faces are segmented into 32 × 2-mm wide strips, ensuring a 2 × 2 mm2 pixel configuration. Eight ionization chambers can be alternatively used as ΔE stages or, if needed, as an additional third layer for more complex triple telescopes. The signals from silicon ΔE layers and from ionization chambers are read by standard electronics, while innovative 32-channel ASIC chips are employed for the readout of the E stages. The results of off-line tests with alpha sources and from the first in-beam experiment with a 17O beam are presented

6. The high granularity and large solid angle detection array EXPADES

2013-12-15

Highlights: • We realized a detection array for Exotic Radioactive Ion Beams. • High granularity (32 × 32 pixels 2 × 2 mm wide for 8 telescopes). • High solid angle (8 telescopes 64 × 64 mm wide in a cylindrical configuration covering up to 2.6 sr). • We tested each component of the array by both alpha particles and in-beam environment. • We measured the angular distribution for {sup 17}O elastic scattering on a {sup 58}Ni target. -- Abstract: The EXPADES (EXotic PArticle DEtection System) detector array consists of 16 Double Side Silicon Strip Detectors (DSSSD) with active areas of 64 × 64 mm{sup 2}, arranged in 8 ΔE (40/50 μm)–E (300 μm) telescopes. All detector faces are segmented into 32 × 2-mm wide strips, ensuring a 2 × 2 mm{sup 2} pixel configuration. Eight ionization chambers can be alternatively used as ΔE stages or, if needed, as an additional third layer for more complex triple telescopes. The signals from silicon ΔE layers and from ionization chambers are read by standard electronics, while innovative 32-channel ASIC chips are employed for the readout of the E stages. The results of off-line tests with alpha sources and from the first in-beam experiment with a {sup 17}O beam are presented.

7. Integration of Antenna Array with Multicrystalline Silicon Solar Cell

O'Conchubhair, Oisin; McEvoy, Patrick; Ammann, Max

2015-01-01

The integration of a low-profile antenna array with a multicrystalline silicon solar cell capable of powering a low-power wireless sensor at 2.45 GHz is reported. Lattice bus bars on the cell are exploited to minimize antenna shadows from low-profile antennas and transmission lines for a higher output power. The dual inverted-F array improves gain, and beam switching enables the array to sweep a wider coverage angle with larger beamwidths compared to other solar integrated antennas.

8. Range-Angle-Dependent Beamforming by Frequency Diverse Array Antenna

Wen-Qin Wang; Huaizong Shao; Jingye Cai

2012-01-01

This paper proposes a range-angle-dependent beamforming for frequency diverse array (FDA) antenna systems. Unlike conventional phased-array antenna, the FDA antenna employs a small amount of frequency increment compared to the carrier frequency across the array elements. The use of frequency increment generates an antenna pattern that is a function of range, time and angle. The range-angle-dependent beamforming allows the FDA antenna to transmit energy over a desired range or angle. This prov...

9. Angle-independent structural colors of silicon

Højlund-Nielsen, Emil; Weirich, Johannes; Nørregaard, Jesper;

2014-01-01

Structural colors are optical phenomena of physical origin, where microscale and nanoscale structures determine the reflected spectrum of light. Artificial structural colors have been realized within recent years. However, multilayer structures require substantial fabrication. Instead we considered...... one-layer surface textures of silicon.We explored four patterns of square structures in a square lattice with periods of 500, 400, 300, and 200 nm. The reflectivity and daylight-colors were measured and compared with simulations based on rigorously coupledwave analysis with excellent agreement. Based...... on the 200-nm periodic pattern, it was found that angle-independent specular colors up to 60 deg of incidence may be provided. The underlying mechanisms include (1) the suppression of diffraction and (2) a strong coupling of light to localized surface states. The strong coupling yields absorption...

10. Time-derivative adaptive silicon photoreceptor array

1991-01-01

We designed and tested a two-dimensional silicon receptor array constructed from pixels that temporally high-pass filter the incident image. There are no surround interactions in the array; all pixels operate independently except for their correlation due to the input image. The high- pass output signal is computed by sampling the output of an adaptive, high-gain, logarithmic photoreceptor during the scanout of the array. After a pixel is sampled, the output of the pixel is reset to a fixed v...

11. Silicon-CsI detector array for heavy-ion reactions

Norbeck, E; Pogodin, P I; Cheng, Y W; Ingram, F D; Bjarki, O; Grévy, S; Magestro, D J; Molen, A M V; Westfall, G D

2000-01-01

An array of 60 silicon-CsI(Tl) detector telescopes has been developed along with associated electronics. The close packing of the telescopes required novel designs for the photodiodes and the silicon DELTA E detectors. Newly developed electronics include preamplifiers, shaping amplifiers, test pulse circuitry, and a module to monitor leakage currents in the silicon diodes. The array covers angles from 5 deg. to 18 deg. in the 4 pi Array at the National Superconducting Cyclotron Laboratory at Michigan State University. It measures protons to 150 MeV and has isotopic resolution for intermediate mass nuclei.

12. Integrated Arrays on Silicon at Terahertz Frequencies

Chattopadhayay, Goutam; Lee, Choonsup; Jung, Cecil; Lin, Robert; Peralta, Alessandro; Mehdi, Imran; Llombert, Nuria; Thomas, Bertrand

2011-01-01

In this paper we explore various receiver font-end and antenna architecture for use in integrated arrays at terahertz frequencies. Development of wafer-level integrated terahertz receiver front-end by using advanced semiconductor fabrication technologies and use of novel integrated antennas with silicon micromachining are reported. We report novel stacking of micromachined silicon wafers which allows for the 3-dimensional integration of various terahertz receiver components in extremely small packages which easily leads to the development of 2- dimensioanl multi-pixel receiver front-ends in the terahertz frequency range. We also report an integrated micro-lens antenna that goes with the silicon micro-machined front-end. The micro-lens antenna is fed by a waveguide that excites a silicon lens antenna through a leaky-wave or electromagnetic band gap (EBG) resonant cavity. We utilized advanced semiconductor nanofabrication techniques to design, fabricate, and demonstrate a super-compact, low-mass submillimeter-wave heterodyne frontend. When the micro-lens antenna is integrated with the receiver front-end we will be able to assemble integrated heterodyne array receivers for various applications such as multi-pixel high resolution spectrometer and imaging radar at terahertz frequencies.

13. Silicon microneedles array with biodegradable tips for transdermal drug delivery

Chen, B; Tay, Francis; Wong, Y T; Iliescu, C

2008-01-01

This paper presents the fabrication process, characterization results and basic functionality of silicon microneedles array with biodegradable tips. In order to avoid the main problems related to silicon microneedles : broking of the top part of the needles inside the skin, a simple solution can be fabrication of microneedles array with biodegradable tips. The silicon microneedles array was fabricated by using reactive ion etching while the biodegradable tips were performed using and anodization process that generates selectively porous silicon only on the top part of the skin. The paper presents also the results of in vitro release of calcein using microneedles array with biodegradable tips

14. Lorentz angle measurements in silicon detectors

Bartsch, V.; Boer, W. de E-mail: wim.de.boer@cern.ch; Bol, J.; Dierlamm, A.; Grigoriev, E.; Hauler, F.; Heising, S.; Herz, O.; Jungermann, L.; Keraenen, R.; Koppenhoefer, M.; Roederer, F.; Schneider, T

2002-02-01

In this paper we study the Lorentz angles of both electrons and holes in magnetic fields up to 8 T and temperatures between 77 and 300 K. This is done before and after irradiating a detector with 21 MeV protons up to a fluence of 10{sup 13}/cm{sup 2}, which is equivalent to {approx}2.8x10{sup 13}/cm{sup 2} 1 MeV neutrons.

15. Nanophotonic production, modulation and switching of ions by silicon microcolumn arrays

Vertes, Akos; Walker, Bennett N.

2013-09-10

The production and use of silicon microcolumn arrays that harvest light from a laser pulse to produce ions are described. The systems of the present invention seem to behave like a quasi-periodic antenna array with ion yields that show profound dependence on the plane of laser light polarization and the angle of incidence. By providing photonic ion sources, this enables enhanced control of ion production on a micro/nano scale and direct integration with miniaturized analytical devices.

16. Nanophotonic production, modulation and switching of ions by silicon microcolumn arrays

Vertes, Akos; Walker, Bennett N.

2012-02-07

The production and use of silicon microcolumn arrays that harvest light from a laser pulse to produce ions are described. The systems of the present invention seem to behave like a quasi-periodic antenna array with ion yields that show profound dependence on the plane of laser light polarization and the angle of incidence. By providing photonic ion sources, this enables enhanced control of ion production on a micro/nano scale and direct integration with miniaturized analytical devices.

17. Angle-resolved diffraction grating biosensor based on porous silicon

Lv, Changwu; Jia, Zhenhong; Liu, Yajun; Mo, Jiaqing; Li, Peng; Lv, Xiaoyi

2016-03-01

In this study, an optical biosensor based on a porous silicon composite structure was fabricated using a simple method. This structure consists of a thin, porous silicon surface diffraction grating and a one-dimensional porous silicon photonic crystal. An angle-resolved diffraction efficiency spectrum was obtained by measuring the diffraction efficiency at a range of incident angles. The angle-resolved diffraction efficiency of the 2nd and 3rd orders was studied experimentally and theoretically. The device was sensitive to the change of refractive index in the presence of a biomolecule indicated by the shift of the diffraction efficiency spectrum. The sensitivity of this sensor was investigated through use of an 8 base pair antifreeze protein DNA hybridization. The shifts of the angle-resolved diffraction efficiency spectrum showed a relationship with the change of the refractive index, and the detection limit of the biosensor reached 41.7 nM. This optical device is highly sensitive, inexpensive, and simple to fabricate. Using shifts in diffraction efficiency spectrum to detect biological molecules has not yet been explored, so this study establishes a foundation for future work.

18. Aluminum-jointed silicon dioxide octagon nanohelix array with desired complex refractive index.

Jen, Yi-Jun; Chen, Chien-Chi; Jheng, Ci-Yao

2014-06-15

In this Letter, glancing angle deposition is used to form an aluminum-jointed silicon dioxide octagon nanohelix array as a 3D nanostructured thin film. As a sculptured metal-dielectric composite, the film exhibits a complex refractive index of near unity with a small imaginary part. This structured film is demonstrated as an efficient light absorber to absorb light in a broad band and over a wide range of angles for both polarization states. PMID:24978492

19. Silicon-based wire electrode array for neural interfaces

Objectives. Metal-wire electrode arrays are widely used to record and stimulate neurons. Commonly, these devices are fabricated from a long insulated metal wire by cutting it into the proper length and using the cross-section as the electrode site. The assembly of a micro-wire electrode array with regular spacing is difficult. With the help of micro-machine technology, a silicon-based wire electrode array (SWEA) is proposed to simplify the assembling process and provide a wire-type electrode with tapered tips. Approach. Silicon wires with regular spacing coated with metal are generated from a silicon wafer through micro-fabrication and are ordered into a 3D array. A silicon wafer is cut into a comb-like structure with hexagonal teeth on both sides by anisotropic etching. To establish an array of silicon-based linear needles through isotropic wet etching, the diameters of these hexagonal teeth are reduced; their sharp edges are smoothed out and their tips are sharpened. The needle array is coated with a layer of parylene after metallization. The tips of the needles are then exposed to form an array of linear neural electrodes. With these linear electrode arrays, an array of area electrodes can be fabricated. Main results. A 6  ×  6 array of wire-type electrodes based on silicon is developed using this method. The time required to manually assemble the 3D array decreases significantly with the introduction of micro-fabricated 2D array. Meanwhile, the tip intervals in the 2D array are accurate and are controlled at no more than 1%. The SWEA is effective both in vitro and in vivo. Significance. Using this method, the SWEA can be batch-prepared in advance along with its parameters, such as spacing, length, and diameter. Thus, neural scientists can assemble proper electrode arrays in a short time. (paper)

20. Broadband high efficiency silicon nanowire arrays with radial diversity within diamond-like geometrical distribution for photovoltaic applications.

Al-Zoubi, Omar H; Said, Tarek M; Alher, Murtadha Abdulmueen; El-Ghazaly, Samir; Naseem, Hameed

2015-07-27

In this study we report novel silicon nanowire (SiNW) array structures that have near-unity absorption spectrum. The design of the new SiNW arrays is based on radial diversity of nanowires with periodic diamond-like array (DLA) structures. Different array structures are studied with a focus on two array structures: limited and broad diversity DLA structures. Numerical electromagnetic modeling is used to study the light-array interaction and to compute the optical properties of SiNW arrays. The proposed arrays show superior performance over other types of SiNW arrays. Significant enhancement of the array absorption is achieved over the entire solar spectrum of interest with significant reduction of the amount of material. The arrays show performance independent of angle of incidence up to 70 degrees, and polarization. The proposed arrays achieved ultimate efficiency as high as 39% with filling fraction as low as 19%. PMID:26367679

1. Multifunctional porous silicon nanopillar arrays: antireflection, superhydrophobicity, photoluminescence, and surface-enhanced Raman scattering

We have fabricated porous silicon nanopillar arrays over large areas with a rapid, simple, and low-cost technique. The porous silicon nanopillars show unique longitudinal features along their entire length and have porosity with dimensions on the single-nanometer scale. Both Raman spectroscopy and photoluminescence data were used to determine the nanocrystallite size to be <3 nm. The porous silicon nanopillar arrays also maintained excellent ensemble properties, reducing reflection nearly fivefold from planar silicon in the visible range without any optimization, and approaching superhydrophobic behavior with increasing aspect ratio, demonstrating contact angles up to 138°. Finally, the porous silicon nanopillar arrays were made into sensitive surface-enhanced Raman scattering (SERS) substrates by depositing metal onto the pillars. The SERS performance of the substrates was demonstrated using a chemical dye Rhodamine 6G. With their multitude of properties (i.e., antireflection, superhydrophobicity, photoluminescence, and sensitive SERS), the porous silicon nanopillar arrays described here can be valuable in applications such as solar harvesting, electrochemical cells, self-cleaning devices, and dynamic biological monitoring. (paper)

2. Silicon pin diode array hybrids for charged particle detection

This paper reports on the design of silicon PIN diode array hybrids for use as charged particle detectors. A brief summary of the need for vertex detectors is presented. Circuitry, block diagrams and device specifications are included

3. Research on silicon microchannel arrays oxide insulation technology

Wu, Ke-xin; Duanmu, Qingduo; Wang, Guozheng; Yang, Ji-kai; Kou, Yang-qiang

2015-03-01

Silicon microchannel plates (Si-MCP) is widely used in the photomultiplier, night vision, X- ray intensifier and other areas. In order to meet the requirements of high voltage electron multiplier, Si-MCP need to prepare a layer of silicon dioxide in the microchannel to improve the insulating properties. There are many methods for preparing SiO2 layer, such as thermal growth, magnetron sputtering method and chemical vapor deposition etc. The thermal oxidation method is often used for preparation of insulating layer that it grows film thickness uniformity, compact structure, simple process and so on. There will be bending deformation phenomenon of silicon microchannel arrays in high temperature oxidation process. The warpage of Si-MCP has brought great for difficulties of subsequent processing. Silicon crystals has the properties of plastic deformation at high temperature, this article take full advantage of this properties by which the already bending deformation of silicon microchannel arrays can be restored to flat.

4. Silicon Field Emission Arrays Coated with CNx Thin Films

Chen Min-gan; Chen Ming-an; Li Jin-chai; Li Jin-chai; Liu Chuan-sheng; Liu Chuan-sheng; Ma You-peng; Ma You-peng; Lu Xian-feng; Lu Xian-feng; Ye Ming-sheng; Ye Ming-sheng

2003-01-01

Arrays of silicon micro-tips were made by etching the p-type (1 0 0) silicon wafers which had SiO2 masks with alkaline solution. The density of the micro-tips is 2 ×104 cm-2. The Scanning Electron Microscope (SEM) photos showed that the tips in these arrays are uniform and orderly.The CNx thin film, with the thickness of 1.27μm was deposited on the silicon micro-tip arrays by using the middle frequency magnetron sputtering technology. The SEM photos showed that the films on the tips are smoothly without particles. Keeping the sharpness of the tips will benefit the properties of field emission. The X-ray photoelectron spectrum (XPS) showed that carbon, nitrogen and oxygen are the three major elements in the surfaces of the films. The percents of them are C: 69.5 %, N: 12.6 % and O: 17.9 %. The silicon arrays coated with CNx thin films had shown a good field emission characterization. The emission current intensity reached 3.2 mA/cm2 at 32.8 V/μm, so it can be put into use. The result showed that the silicon arrays coated with CNx thin films are likely to be good field emission cathode.The preparation and the characterization of the samples were discussed in detail.

5. Silicon Field Emission Arrays Coated with CNx Thin Films

ChertMing-an; LiJin-chai; LiuChuan-sheng; MaYou-peng; LuXlan-feng; YeMing-sheng

2003-01-01

Arrays of silicon micro-tips were made by etching the p-type (1 0 0) silicon wafers which had SiO2 masks with alkaline solution. The density of the micro-tips is 2 ×104 cm-2. The Scanning Electron Microscope (SEM) photos showed that the tips in these arrays are uniform and orderly.The CNx thin film, with the thickness of 1.27μm was deposited on the silicon micro-tip arrays by using the middle frequency magnetron sputtering technology. The SEM photos showed that the films on the tips are smoothly without particles. Keeping the sharpness of the tips will benefit the properties of field emission. The X-ray photoelectron spectrum (XPS) showed that carbon, nitrogen and oxygen are the three major elements in the surfaces of the films. The percents of them are C: 69.5 %, N: 12. 6 % and O: 17.9 %. The silicon arrays coated with CNx thin films had shown a good field emission characterization. The emission current intensity reached 3. 2 mA/cm2 at 32.8 V/μm, so it can be put into use. The result showed that the silicon arrays coated with CNx thin films are likely to be good field emission cathode.The preparation and the characterization of the samples were discussed in detail.

6. Experimental study on silicon micro-heat pipe arrays

Launay, S.; Sartre, V.; Lallemand, M. [Institut National des Sciences Appliquees, Villeurbanne (France). Centre de Thermique

2004-02-01

In this study, micro-heat pipe arrays etched into silicon wafers have been investigated for electronic cooling purposes. Micro-heat pipes of triangular cross-section and with liquid arteries were fabricated by wet anisotropic etching with a KOH solution. The microchannels (230 {mu}m wide) are closed by molecular bonding of a plain wafer with the grooved one. A test bench was developed for the micro-heat pipe filling and the thermal characterisation. The temperature profile on the silicon surface is deduced from experimental measurements. The results show that with the artery micro-heat pipe array, filled with methanol, the effective thermal conductivity of the silicon wafer is significantly improved compared to massive silicon. (author)

7. Directional imbibition on a chemically patterned silicon micropillar array.

Jokinen, Ville

2016-01-20

Directional imbibition of oils (hexadecane, tetradecane, and dodecane) and water is demonstrated on a chemically patterned silicon micropillar array. Four different directional imbibition types are shown: unidirectional, two types of bidirectional and tridirectional imbibition. The surfaces consist of a silicon micropillar array with an overlaid surface chemistry pattern. This configuration leads to anisotropic wetting behaviour into various directions of the advancing meniscus. Due to the free energy landscape obtained, the advancing meniscus gets pinned in some directions (determined by the surface chemistry pattern) while it is free to move to the remaining directions. The conditions for directional imbibition and design criteria for the surfaces are derived and discussed. PMID:26576647

8. ISPA (imaging silicon pixel array) experiment

Patrice Loïez

2002-01-01

The ISPA tube is a position-sensitive photon detector. It belongs to the family of hybrid photon detectors (HPD), recently developed by CERN and INFN with leading photodetector firms. HPDs confront in a vacuum envelope a photocathode and a silicon detector. This can be a single diode or a pixelized detector. The electrons generated by the photocathode are efficiently detected by the silicon anode by applying a high-voltage difference between them. ISPA tube can be used in high-energy applications as well as bio-medical and imaging applications.

9. ISPA (imaging silicon pixel array) experiment

Patrice Loïez

2002-01-01

Application components of ISPA tubes are shown: the CERN-developed anode chip, special windows for gamma and x-ray detection, scintillating crystal and fibre arrays for imaging and tracking of ionizing particles.

10. ISPA (imaging silicon pixel array) experiment

Patrice Loïez

2002-01-01

The bump-bonded silicon pixel detector, developed at CERN by the EP-MIC group, is shown here in its ceramic carrier. Both represent the ISPA-tube anode. The chip features between 1024 (called OMEGA-1) and 8196 (ALICE-1) active pixels.

11. ISPA (imaging silicon pixel array) experiment

Patrice Loïez

2002-01-01

On the table, under the scrutiny of some collaboration members, an ISPA tube (upper-left of the table) with some of its application components is shown: they consist of the CERN-developed anode chip, special windows for gamma and x-ray detection, scintillating crystal and fibre arrays for imaging and tracking of ionizing particles.

12. Lorentz angle measurements in irradiated silicon detectors between 77 and 300 K

Boer, W. de; Bol, J.; Dierlamm, A.; Grigoriev, E.; Hauler, F.; Heising, S. E-mail: stephan.heising@cern.ch; Herz, O.; Jungermann, L.; Keraenen, R.; Koppenhoefer, M.; Roederer, F.; Schneider, T

2001-04-01

Future experiments are using silicon detectors in a high radiation environment and in high magnetic fields. The radiation tolerance of silicon improves by cooling it to temperatures of approximately 130 K. Charge carriers generated in silicon by traversing particles are deflected due to the Lorentz force. We present measurements of the Lorentz angle in irradiated silicon detectors between 77 and 300 K. These results and the ones obtained from non-irradiated detectors are compared with simulations.

13. Arrays of ultrathin silicon solar microcells

Rogers, John A.; Rockett, Angus A.; Nuzzo, Ralph; Yoon, Jongseung; Baca, Alfred

2015-08-11

Provided are solar cells, photovoltaics and related methods for making solar cells, wherein the solar cell is made of ultrathin solar grade or low quality silicon. In an aspect, the invention is a method of making a solar cell by providing a solar cell substrate having a receiving surface and assembling a printable semiconductor element on the receiving surface of the substrate via contact printing. The semiconductor element has a thickness that is less than or equal to 100 .mu.m and, for example, is made from low grade Si.

14. Silicon Array for Multi-particle Emission

XU; Xin-xing; LIN; Cheng-jian; SUN; Li-jie; BAO; Peng-fei; YANG; Lei; YANG; Feng; ZHANG; Huan-qiao; LIU; Zu-hua; JIA; Hui-ming; MA; Nan-ru

2013-01-01

Remarkable progress in the study of two-proton emission has been made in recent years.One of the next destinations is the realization of high-precision direct measurements of decay-energy and emission-angle correlations inβ-delayed two-proton(β2p)emission.We have studiedβ2p correlated emission of the ground state of 26P at the proton drip line with the direct measurement at the National

15. Photoluminescence Properties of Silicon Nanowires and Carbon Nanotube-Silicon Nanowire Composite Arrays

李梦轲; 陆梅; 孔令斌; 王成伟; 郭新勇; 力虎林

2002-01-01

Composite arrays of multi-wall carbon nanotubes (MWNTs) and silicon nanowires (SiNWs) are fabricated by means of the chemical vapour deposition method in porous anodic aluminium oxide (AAO) templates. The results of the scanning electron microscopy, high-resolution transmission electron microscopy, and transmission electron microscopy have shown that SiNWs are successful nested or filled in the hollow cavities of synthesized MWNT arrays in AAO templates to form MWNT-SiNW composite arrays. The photoluminescence (PL) intensity degradation and a blueshift of PL peak position, usually created from the chemical instability of the SiNW surfaces, are decreased and eliminated clearly in the composite arrays. The composite arrays of MWNTs-SiNWs exhibit more enhanced intensity and stability of PL performance than the SiNW arrays deposited in AAO templates.

16. The Surface Photovoltage Mechanism of a Silicon Nanoporous Pillar Array

Hu, Zhen-Gang; Tian, Yong-Tao; Li, Xin-Jian

2013-08-01

The surface photovoltage (SPV) mechanism of a silicon nanoporous pillar array (Si-NPA) is investigated by using SPV spectroscopy in different external electric fields. Through comparisons with the SPV spectrum of single crystal silicon (sc-Si), the silicon nano-crystallite (nc-Si)/SiOx nanostructure of Si-NPA is proved to be capable of producing obvious SPV in the wavelength range 300-580 nm. The SPV for the sc-Si layer and the nc-Si/SiOx nanostructure has shown certain contrary characters in different external electric fields. Through analysis, the localized states in the amorphous SiOx matrix are believed to dominate the SPV for the nc-Si/SiOx nanostructure.

17. Amorphous Silicon 16—bit Array Photodetector①

ZHANGShaoqiang; XUZhongyang; 等

1997-01-01

An amorphous silicon 16-bit array photodetector with the a-SiC/a-Si heterojunction diode is presented.The fabrication processes of the device were studied systematically.By the optimum of the diode structure and the preparation procedures,the diode with Id<10-12A/mm2 and photocurrentIp≥0.35A/W has been obtained at the wavelength of 632nm.

18. Silicon nanoporous pillar array and its surface copper deposition

FU Xiaonan; CHAI Huadou; LI Xinjian

2005-01-01

Silicon nanoporous pillar array (Si-NPA) has been prepared by a hydrothermal etching technique. Using Si-NPA as substrate, a Cu/Si-NPA nanocomposite thin film has been obtained with immersion plating method. Morphological and structural analysis indicates that Si-NPA is a typical structural composite system characterized by a triple hierarchical structure, i. e. the array of micron-sized silicon pillars, the nanopores densely distributed on the surface of the pillars, and the silicon nanocrystallites that constitute the pore walls. Cu/Si-NPA inherits the morphological characteristics of Si-NPA. The compactability of the deposited copper nanoparticles varies alternatively with the local geometrical features of Si-NPA and forms a quasi-periodical pattern. Such an experimental phenomenon is attributed to the velocity dependence of the copper deposition upon the local geometrical features of Si-NPA. These results indicate that Si-NPA might be used as an ideal template for preparing specially patterned, structured or functionalized metal/ silicon nanocomposite systems.

19. Silicon drift photodetector arrays for the HICAM gamma camera

Silicon drift detectors (SDDs) have shown to be a competitive device for the readout of scintillators with respect to conventional photodetectors, thanks to their high quantum efficiency and low electronics noise. Recently, they have been successfully employed in first small prototypes of Anger cameras to achieve sub-millimeter spatial resolution in gamma-ray imaging. To cover larger formats of Anger cameras, in particular in the framework of the HICAM project, specially focused on human imaging, we have developed new SDD arrays of larger active areas. To assemble photodetector planes of several cm2, we have designed a basic unit composed by a linear array of 5 SDDs of 1 cm2 active area each. In this work, we present the results of the experimental characterization of these photodetector arrays in direct X-ray detection to evaluate the electronics noise, as well as gamma-ray detection with a scintillator.

20. Deployable aerospace PV array based on amorphous silicon alloys

Hanak, Joseph J.; Walter, Lee; Dobias, David; Flaisher, Harvey

1989-01-01

The development of the first commercial, ultralight, flexible, deployable, PV array for aerospace applications is discussed. It is based on thin-film, amorphous silicon alloy, multijunction, solar cells deposited on a thin metal or polymer by a proprietary, roll-to-roll process. The array generates over 200 W at AM0 and is made of 20 giant cells, each 54 cm x 29 cm (1566 sq cm in area). Each cell is protected with bypass diodes. Fully encapsulated array blanket and the deployment mechanism weigh about 800 and 500 g, respectively. These data yield power per area ratio of over 60 W/sq m specific power of over 250 W/kg (4 kg/kW) for the blanket and 154 W/kg (6.5 kg/kW) for the power system. When stowed, the array is rolled up to a diameter of 7 cm and a length of 1.11 m. It is deployed quickly to its full area of 2.92 m x 1.11 m, for instant power. Potential applications include power for lightweight space vehicles, high altitude balloons, remotely piloted and tethered vehicles. These developments signal the dawning of a new age of lightweight, deployable, low-cost space arrays in the range from tens to tens of thousands of watts for near-term applications and the feasibility of multi-100 kW to MW arrays for future needs.

1. Stable divergence angles of a magnetic dipole spiral array

Fan, X.D.; Bursill, L.A.

1996-03-01

An analytical model is introduced for Douady and Couder`s [1992] experiment, where phyllotactic patterns appear as a dynamical result of the interaction between magnetic dipoles. The difference equation for the divergence angle (i.e. the angle between successive radial vectors) is obtained by solving the equations of motion with a second nearest neighbour (SNN) approximation. A one dimensional map analysis as well as a comprehensive analytical proof shows that the divergence angle always converges to a single attractor regardless of the initial conditions. This attractor is approximately the Fibonacci angle ({approx} 138 deg) within variations due to a growth factor {mu} of the pattern. The system is proved to be stable with the SNN approximation. Further analysis with a third nearest neighbour approximation (TNN) shows extra linearly stable attractors may appear around the Lucas angle at {approx} 99.5 deg. 7 refs., 5 figs.

2. A silicon array detector for high-energy betas

The detection of significant levels of certain gamma and beta emitting isotopes could allow on-site Inspection teams working under the Comprehensive Test Ban Treaty to localize probable vent and fissure locations. Thus, sophisticated drilling and radionuclide measurements could then be made more effectively allowing for a higher probability of correctly identifying a nuclear event. In order to address this need we have developed a silicon array coupled with a Nal for detecting gammas, high-energy betas, and beta-gamma coincidences. The pursuit of this detection method is now viable since large-area, high-purity silicon wafers are now commercially available making this layered, large-area technique technically and economically feasible. We have designed, constructed, and tested a prototype detector system and we will present out initial test data

3. Wide-Angle X-Band Antenna Array with Novel Radiating Elements

R. Chernobrovkin

2008-06-01

Full Text Available An antenna array with wide-angle beam steering is presented in this paper. The antenna consists of dielectrically filled open-ended waveguides with a new type of excitation as individual radiators. The characteristics of the radiator have been analyzed. The novel radiator has a wide beamwidth and the frequency band of around 21%. Following the computational modeling and experimental investigations the characteristics of the antenna array for scan angles up to 50° are discussed.

4. Demonstration of lasercom and spatial tracking with a silicon Geiger-mode APD array

Yarnall, Timothy M.; Horkley, Benjamin W.; Garg, Ajay S.; Hamilton, Scott A.

2016-03-01

We present a demonstration of a high-rate photon counting receiver with the potential to act as a spatial tracker based on a silicon Geiger-mode avalanche photodiode array (GM-APD). This array enables sensitive high-rate optical communication in the visible and near infrared regions of the spectrum. The array contains 1024 elements arranged in a 32x32 pixel square. This large number of elements supports high data rates through the mitigation of blocking losses and associated data rate limitations created by the reset time of an individual Geiger-mode detector. Measurement of bit error rates demonstrate that receiver sensitivities of 2.55 dB (detected) photons-per-bit for 78.8 Mb/s on-off-keying and -0.46 dB (detected) photons-per-bit for 19.4 Mb/s 16-ary pulse-position modulation are accessible with strong forward error correction. Additionally, the array can record the spatial coordinates of each detection event. By computing the centroid of the distribution of spatial detections it is possible to determine the angle-of-arrival of the detected photons. These levels of performance imply that Si GM-APD arrays are excellent candidates for a variety of free space lasercom applications ranging from atmospheric communication in the 1 micron or 780 nm spectral windows to underwater communication in the 480 nm to 520 nm spectral window

5. Optimized antireflective silicon nanostructure arrays using nanosphere lithography

Lee, Dohaeng; Bae, Jiwoong; Hong, Soonwook; Yang, Hwichul; Kim, Young-Beom

2016-05-01

Broadband optical antireflective arrays of sub-wavelength structures were fabricated on silicon substrates using colloidal nanosphere lithography in conjunction with reactive ion etching. The morphology of the nanostructures, including the shape, base diameter and height, was precisely controlled by modifying the conventional process of nanosphere lithography. We investigated their effects on the optical characteristics based on experimentally measured reflectance performance. The Si nanostructure arrays demonstrated optical antireflection performance with an average reflectance of about 1% across the spectral range from 300 to 800 nm, i.e. near-ultraviolet to visible wavelengths. This fabrication method can be used to create a large surface area and offers a promising approach for antireflective applications.

6. Silicone Brushes: Omniphobic Surfaces with Low Sliding Angles.

Wooh, Sanghyuk; Vollmer, Doris

2016-06-01

Losing contact: Omniphobic surfaces can be readily produced by acid-catalyzed graft polycondensation of dimethyldimethoxysilane (PDMS). Droplets show a very small contact angle hysteresis as well as a low sliding angle of only a few degrees. The nm-thick PDMS layer is neither easily washed away nor depleted. This method offers a novel approach towards the preparation of super-liquid-repelling surfaces. PMID:27159802

7. Composite silicon nanostructure arrays fabricated on optical fibre by chemical etching of multicrystal silicon film

Integrating nanostructures onto optical fibers presents a promising strategy for developing new-fashioned devices and extending the scope of nanodevices’ applications. Here we report the first fabrication of a composite silicon nanostructure on an optical fiber. Through direct chemical etching using an H2O2/HF solution, multicrystal silicon films with columnar microstructures are etched into a vertically aligned, inverted-cone-like nanorod array embedded in a nanocone array. A faster dissolution rate of the silicon at the void-rich boundary regions between the columns is found to be responsible for the separation of the columns, and thus the formation of the nanostructure array. The morphology of the nanorods primarily depends on the microstructure of the columns in the film. Through controlling the microstructure of the as-grown film and the etching parameters, the structural control of the nanostructure is promising. This fabrication method can be extended to a larger length scale, and it even allows roll-to-roll processing. (paper)

8. Silicon nitride Micromesh Bolometer Array for Submillimeter Astrophysics.

Turner, A D; Bock, J J; Beeman, J W; Glenn, J; Hargrave, P C; Hristov, V V; Nguyen, H T; Rahman, F; Sethuraman, S; Woodcraft, A L

2001-10-01

We present the design and performance of a feedhorn-coupled bolometer array intended for a sensitive 350-mum photometer camera. Silicon nitride micromesh absorbers minimize the suspended mass and heat capacity of the bolometers. The temperature transducers, neutron-transmutation-doped Ge thermistors, are attached to the absorber with In bump bonds. Vapor-deposited electrical leads address the thermistors and determine the thermal conductance of the bolometers. The bolometer array demonstrates a dark noise-equivalent power of 2.9 x 10(-17) W/ radicalHz and a mean heat capacity of 1.3 pJ/K at 390 mK. We measure the optical efficiency of the bolometer and feedhorn to be 0.45-0.65 by comparing the response to blackbody calibration sources. The bolometer array demonstrates theoretical noise performance arising from the photon and the phonon and Johnson noise, with photon noise dominant under the design background conditions. We measure the ratio of total noise to photon noise to be 1.21 under an absorbed optical power of 2.4 pW. Excess noise is negligible for audio frequencies as low as 30 mHz. We summarize the trade-offs between bare and feedhorn-coupled detectors and discuss the estimated performance limits of micromesh bolometers. The bolometer array demonstrates the sensitivity required for photon noise-limited performance from a spaceborne, passively cooled telescope. PMID:18364768

9. Measurement of small angle based on a (1 0 0) silicon wafer and heterodyne interferometer

Hsieh, Meng-Chang; Lin, Jiun-You; Chen, Yu-Fong; Chang, Chia-Ou

2016-06-01

In this paper, a new optical material application and a heterodyne interferometer are proposed for measuring small angles. In the proposed interferometer, the optical material is a (1 0 0) silicon wafer applied to compose a new architecture of small angle sensor. The small angle measurement used the phase difference which is dependent on the incident angle at the silicon wafer surface to deduce the angular variation. The proposed architecture is simple and uses the common path method to compare test and reference signals; thus, small angles can be easily and accurately measured by estimating the phase difference. The experimental results demonstrate the feasibility of this method. The angular resolution and sensitivity levels superior to 7 × 10-5° (1.3 × 10-6 rad) and 150 (deg/deg), respectively, were attainable in a dynamic range of 0.45°.

10. Method of rotation angle measurement in machine vision based on calibration pattern with spot array

We propose a method of rotation angle measurement with high precision in machine vision. An area scan CCD camera, imaging lens, and calibration pattern with a spot array make up the measurement device for measuring the rotation angle. The calibration pattern with a spot array is installed at the rotation part, and the CCD camera is set at a certain distance from the rotation components. The coordinates of the spots on the calibration pattern is acquired through the vision image of the calibration pattern captured by the CCD camera. At the initial position of the calibration pattern, the camera is calibrated with the spot array; the mathematical model of distortion error of the CCD camera is built. With the equation of coordinate rotation measurement, the rotation angle of the spot array is detected. In the theoretic simulation, noise of different levels is added to the coordinates of the spot array. The experiment results show that the measurement device can measure the rotation angle precisely with a noncontact method. The standard deviation of rotation angle measurement is smaller than 3 arc sec. The measurement device can measure both microangles and large angles.

11. Contact Angles and Surface Tension of Germanium-Silicon Melts

Croell, A.; Kaiser, N.; Cobb, S.; Szofran, F. R.; Volz, M.; Rose, M. Franklin (Technical Monitor)

2001-01-01

Precise knowledge of material parameters is more and more important for improving crystal growth processes. Two important parameters are the contact (wetting) angle and the surface tension, determining meniscus shapes and surface-tension driven flows in a variety of methods (Czochralski, EFG, floating-zone, detached Bridgman growth). The sessile drop technique allows the measurement of both parameters simultaneously and has been used to measure the contact angles and the surface tension of Ge(1-x)Si(x) (0 less than or equal to x less than or equal to 1.3) alloys on various substrate materials. Fused quartz, Sapphire, glassy carbon, graphite, SiC, carbon-based aerogel, pyrolytic boron nitride (pBN), AIN, Si3N4, and polycrystalline CVD diamond were used as substrate materials. In addition, the effect of different cleaning procedures and surface treatments on the wetting behavior were investigated. Measurements were performed both under dynamic vacuum and gas atmospheres (argon or forming gas), with temperatures up to 1100 C. In some experiments, the sample was processed for longer times, up to a week, to investigate any changes of the contact angle and/or surface tension due to slow reactions with the substrate. For pure Ge, stable contact angles were found for carbon-based substrates and for pBN, for Ge(1-x)Si(x) only for pBN. The highest wetting angles were found for pBN substrates with angles around 170deg. For the surface tension of Ge, the most reliable values resulted in gamma(T) = (591- 0.077 (T-T(sub m)) 10(exp -3)N/m. The temperature dependence of the surface tension showed similar values for Ge(1-x)Si(x), around -0.08 x 10(exp -3)N/m K, and a compositional dependence of 2.2 x 10(exp -3)N/m at%Si.

12. Polarization rotator of arbitrary angle based on simple slot-array

Liu, Xiaoming; Cao, Xiaohang; Yu, Junsheng; Chen, Xiaodong; Yao, Yuan; Qi, Limei; Chen, Zhijiao; Zhou, Jun

2015-12-01

A novel polarization rotator of arbitrary angle was proposed and realized based on simple slot arrays. To achieve the rotation of an arbitrary angle α, the slots on the first layer have to be at an angle of α to the slots on the second layer. Consequently, 90° rotation can be realized using two perpendicularly oriented slot arrays, which overturns the conventional notion of that perpendicular slot arrays are not possible to pass electromagnetic wave. In addition, such structure provides the same bandwidth comparing to its counterpart utilized for frequency selective surface (FSS). Furthermore, such structure is much easier to be fabricated compared to the substrate integrated waveguide (SIW) array. Moreover, low insertion loss can be achieved based on metallic material.

13. Polarization rotator of arbitrary angle based on simple slot-array

Xiaoming Liu

2015-12-01

Full Text Available A novel polarization rotator of arbitrary angle was proposed and realized based on simple slot arrays. To achieve the rotation of an arbitrary angle α, the slots on the first layer have to be at an angle of α to the slots on the second layer. Consequently, 90° rotation can be realized using two perpendicularly oriented slot arrays, which overturns the conventional notion of that perpendicular slot arrays are not possible to pass electromagnetic wave. In addition, such structure provides the same bandwidth comparing to its counterpart utilized for frequency selective surface (FSS. Furthermore, such structure is much easier to be fabricated compared to the substrate integrated waveguide (SIW array. Moreover, low insertion loss can be achieved based on metallic material.

14. Ordered arrays of silicon pillars with controlled height and aspect ratio

We report the fabrication of ordered arrays of silicon pillars via a combination of nanosphere lithography (NSL) and reactive ion etching (RIE). For NSL we used monolayers of silica particles self-assembled onto silicon substrates as masks for the deposition of hexagonal arrays of chromium nanoislands. By changing the amount of the deposited metal we fabricated arrays of nanoislands with different size and spacing. By using these arrays as masks for RIE, silicon pillars with different height (up to 1100 nm) and aspect ratio (up to 12:1) could be obtained

15. Smart integration of silicon nanowire arrays in all-silicon thermoelectric micro-nanogenerators

Fonseca, Luis; Santos, Jose-Domingo; Roncaglia, Alberto; Narducci, Dario; Calaza, Carlos; Salleras, Marc; Donmez, Inci; Tarancon, Albert; Morata, Alex; Gadea, Gerard; Belsito, Luca; Zulian, Laura

2016-08-01

Micro and nanotechnologies are called to play a key role in the fabrication of small and low cost sensors with excellent performance enabling new continuous monitoring scenarios and distributed intelligence paradigms (Internet of Things, Trillion Sensors). Harvesting devices providing energy autonomy to those large numbers of microsensors will be essential. In those scenarios where waste heat sources are present, thermoelectricity will be the obvious choice. However, miniaturization of state of the art thermoelectric modules is not easy with the current technologies used for their fabrication. Micro and nanotechnologies offer an interesting alternative considering that silicon in nanowire form is a material with a promising thermoelectric figure of merit. This paper presents two approaches for the integration of large numbers of silicon nanowires in a cost-effective and practical way using only micromachining and thin-film processes compatible with silicon technologies. Both approaches lead to automated physical and electrical integration of medium-high density stacked arrays of crystalline or polycrystalline silicon nanowires with arbitrary length (tens to hundreds microns) and diameters below 100 nm.

16. Preparation of Periodically Arrayed Silicon Microwires Using Simple Patterning Process.

Kim, Changheon; Lim, Sangwoo; Jeong, Chaehwan

2015-11-01

The silicon (Si) microwires were fabricated by microsphere lithography using polystyrene (PS) beads monolayer. The Si wafer tailored into 40 x 40 mm2 was used as a substrate. The monolayer of 2.0 μm-sized PS beads was formed on substrates through convective assembly method. PS beads on substrates were tailored into smaller sizes by O2 plasma treatment using reactive ion etching (RIE). This controllable re-sizing process gave an opportunity to prepare the wire-array with various radii of Si microwires fabricated by using inductively coupled plasma (ICP)-etching. The convective assembly process was monitored in real-time through an optical microscope with a CCD camera. PS beads and structures of Si microwires were characterized using a scanning electron microscope (SEM) and the optical property was measured by the UV-Vis spectroscopy. PMID:26726546

17. Static and dynamic characterization of robust superhydrophobic surfaces built from nano-flowers on silicon micro-post arrays

Chen, Longquan

2010-09-01

Superhydrophobic nano-flower surfaces were fabricated using MEMS technology and microwave plasma-enhanced chemical vapor deposition (MPCVD) of carbon nanotubes on silicon micro-post array surfaces. The nano-flower structures can be readily formed within 1-2 min on the micro-post arrays with the spacing ranging from 25 to 30 μm. The petals of the nano-flowers consisted of clusters of multi-wall carbon nanotubes. Patterned nano-flower structures were characterized using various microscopy techniques. After MPCVD, the apparent contact angle (160 ± 0.2°), abbreviated as ACA (defined as the measured angle between the apparent solid surface and the tangent to the liquid-fluid interface), of the nano-flower surfaces increased by 139% compared with that of the silicon micro-post arrays. The measured ACA of the nano-flower surface is consistent with the predicted ACA from a modified Cassie-Baxter equation. A high-speed CCD camera was used to study droplet impact dynamics on various micro/nanostructured surfaces. Both static testing (ACA and sliding angle) and droplet impact dynamics demonstrated that, among seven different micro/nanostructured surfaces, the nano-flower surfaces are the most robust superhydrophobic surfaces. © 2010 IOP Publishing Ltd.

18. Static and dynamic characterization of robust superhydrophobic surfaces built from nano-flowers on silicon micro-post arrays

Superhydrophobic nano-flower surfaces were fabricated using MEMS technology and microwave plasma-enhanced chemical vapor deposition (MPCVD) of carbon nanotubes on silicon micro-post array surfaces. The nano-flower structures can be readily formed within 1–2 min on the micro-post arrays with the spacing ranging from 25 to 30 µm. The petals of the nano-flowers consisted of clusters of multi-wall carbon nanotubes. Patterned nano-flower structures were characterized using various microscopy techniques. After MPCVD, the apparent contact angle (160 ± 0.2°), abbreviated as ACA (defined as the measured angle between the apparent solid surface and the tangent to the liquid–fluid interface), of the nano-flower surfaces increased by 139% compared with that of the silicon micro-post arrays. The measured ACA of the nano-flower surface is consistent with the predicted ACA from a modified Cassie–Baxter equation. A high-speed CCD camera was used to study droplet impact dynamics on various micro/nanostructured surfaces. Both static testing (ACA and sliding angle) and droplet impact dynamics demonstrated that, among seven different micro/nanostructured surfaces, the nano-flower surfaces are the most robust superhydrophobic surfaces

19. Develop silicone encapsulation systems for terrestrial silicon solar arrays. First quarterly progress report, February 15, 1978--June 30, 1978

1978-07-10

This study is directed toward the development of a cost effective encapsulation system for photovoltaic modules using silicone based materials. This is a cooperative effort between Dow Corning, the major supplier of silicones and silicone intermediates, and Spectrolab a leading photovoltaic array manufacturer. The total contract effort has been divided into four tasks: technology review, generation of screening concepts, assessment of encapsulation concepts, and evaluation of encapsulation concepts. A review of technology pertinent to the use and weatherability of silicone based materials and a plan for screening encapsulation concepts are presented. The technology review covered: the performance of clear silicones in weathering and stress environments, photovoltaic industry experience with silicone materials used in photovoltaic systems, and silicones used in the protection of electronic devices.

20. Wide-viewing-angle three-dimensional display system using HOE lens array

Takahashi, Hideya; Fujinami, Hiromitsu; Yamada, Kenji

2006-02-01

Integral imaging has the problem of the limitation of viewing angle. This paper describes a wide-viewing-angle 3D display system using holographic optical element (HOE) lens array. This display system consists of a flat HOE lens array and a projector. However, the axis of each elemental HOE lens is eccentric. Since every axis of the elemental HOE lens is convergent, the flat HOE lens array works as a virtual curved lens array. Thus, this display system has a wide viewing angle. On the other hand, generally, in a integral imaging system each elemental lens has its corresponding area on the display panel. To prevent the image flipping, the elemental image that exceeds the corresponding area is discarded. Therefore, the number of the elemental images is limited and the viewing angle is limited. In the proposed system, since the HOE lens array is flat and the light rays from the projector are parallel, the elemental image does not exceed the corresponding area and the flipped images are not observed. Also, the configuration of this display system is simple. The principle of the proposed system is explained and the experimental result is presented.

1. Comparison of steering angle and bandwidth for various phased array antenna concepts

Bonjour, Romain; Singleton, Matthew; Leuchtmann, Pascal; Leuthold, Juerg

2016-08-01

In this paper we compare different integratable ultra-fast tunable true-time delay concepts with respect to their performances in a phased array system. The performances of the schemes are assessed with respect to the supported range, i.e. the range within which beam steering for a given fractional bandwidth can be achieved with a gain flatness better than 3 dB. We also compare the array gain as of function of steering angle and fractional bandwidth.

2. Graded index and randomly oriented core-shell silicon nanowires for broadband and wide angle antireflection

P. Pignalosa

2011-09-01

Full Text Available Antireflection with broadband and wide angle properties is important for a wide range of applications on photovoltaic cells and display. The SiOx shell layer provides a natural antireflection from air to the Si core absorption layer. In this work, we have demonstrated the random core-shell silicon nanowires with both broadband (from 400nm to 900nm and wide angle (from normal incidence to 60º antireflection characteristics within AM1.5 solar spectrum. The graded index structure from the randomly oriented core-shell (Air/SiOx/Si nanowires may provide a potential avenue to realize a broadband and wide angle antireflection layer.

3. Angled microfiber arrays as low-modulus, low Poisson's ratio compliant substrates

This paper presents a novel fabrication method for producing high-aspect-ratio, angled polymer microfiber arrays by directional pulling of polyethylene from low-aspect-ratio, microporous polycarbonate templates. These arrays represent a novel substrate for electrostatic sensors and actuators because they are characterized by low stiffness (<24 kPa effective elastic modulus), low Poisson's ratio (effectively zero at low strains), and very low density (<1% of solid polyethylene). Validation of these properties is presented by developing a model based on elastica theory, and by performing experiments using a parallel-plate electrostatic actuator fabricated with a fiber array as the dielectric and return spring. (paper)

4. Angle-Polarization Estimation for Coherent Sources with Linear Tripole Sensor Arrays.

Wang, Kun; He, Jin; Shu, Ting; Liu, Zhong

2016-01-01

We propose a parallel factor (PARAFAC) analysis-based angle and polarization estimation algorithm for multiple coherent sources using a uniformly-spaced linear tripole sensor array. By forming a PARAFAC model using the spatial signature of the tripole array, the new algorithm requires neither spatial smoothing nor vector-field smoothing to decorrelate the signal coherency. We also establish that the angle-polarization parameters of K coherent signals can be uniquely determined by PARAFAC analysis, as long as the number of tripoles L ≥ 2K - 1 . In addition, the proposed algorithm can offer enhanced angle and polarization estimation accuracy by extending the interspacing of the tripoles beyond a half wavelength. PMID:26907273

5. Angle-Polarization Estimation for Coherent Sources with Linear Tripole Sensor Arrays

Kun Wang

2016-02-01

Full Text Available We propose a parallel factor (PARAFAC analysis-based angle and polarization estimation algorithm for multiple coherent sources using a uniformly-spaced linear tripole sensor array. By forming a PARAFAC model using the spatial signature of the tripole array, the new algorithm requires neither spatial smoothing nor vector-field smoothing to decorrelate the signal coherency. We also establish that the angle-polarization parameters of K coherent signals can be uniquely determined by PARAFAC analysis, as long as the number of tripoles L ≥ 2K − 1 . In addition, the proposed algorithm can offer enhanced angle and polarization estimation accuracy by extending the interspacing of the tripoles beyond a half wavelength.

6. Silicon nanopillar arrays with SiO2 overlayer for biosensing application

Choudhury, B. Dev; Casquel del Campo, Rafael; Bañuls, María José; Sanza Gutierrez, Francisco Javier; Laguna Heras, Maria Fe; Holgado Bolaños, Miguel; Puchades, Rosa; Maquieira, Ángel; Angulo Barrios, Carlos; Anand, S.

2014-01-01

We present the fabrication of silicon dioxide (SiO2) coated silicon nanopillar array structures and demonstrate their application as sensitive optical biosensors. Colloidal lithography, plasma dry etching and deposition processes are used to fabricate SiO2 coated Si nanopillar arrays with two different diameters and periods. Proof of concept bio recognition experiments are carried out with the bovine serum albumin (BSA)/antiBSA model system using Fourier transform visible and IR spectrometry ...

7. Small angle X-ray scattering study of oxygen precipitation in silicon

Czochralski-grown dislocation-free silicon is used in the semiconductor industry almost exclusively for manufacturing VLSI devices. Such material contains small quantities (∼20 ppm) of dissolved oxygen, which can have a crucial effect on the properties of produced devices. Therefore it is of great importance to study its precipitation in a silicon matrix after given thermal treatment. The small angle X-ray scattering (SAXS) technique was used to study oxygen precipitation in monocrystalline silicon samples. We used 8 and 16 keV radiation to overcome the high absorption at low energies. A series of samples has been prepared with controlled sequence of oxygen nucleation and precipitation phase and measured with SAXS. It is shown that this low contrast changes in standard wafers can be investigated using synchrotron radiation

8. Incidence angle and spectral effects on vertical junction silicon solar cell capacitance

SANE, MOUSTAPHA; ŞAHİN, Gökhan; BARRO, Fabé Idrissa; MAIGA, Amadou Seidou

2014-01-01

The aim of this work is to present a theoretical study of a vertical junction silicon solar cell under monochromatic illumination. By solving the continuity equation and using a one-dimensional model in frequency modulation, we derive the analytical expressions of both excess minority carrier density and photovoltage. Based on these expressions, the solar cell capacitance was calculated; we then exhibited the effects of both illumination wavelength and incidence angle on the solar cell capaci...

9. INVESTIGATION ON SILICON SOLAR CELL CAPACITANCE AND ITS DEPENDENCE ON BOTH TEMPERATURE AND INCIDENCE ANGLE

Moustapha Sané

2014-01-01

The aim of this work is to investigate a theoretical study of a vertical junction silicon solar cell capacitance under monochromatic illumination. By solving the continuity equation and using a one dimensional model in frequency modulation, we derive the analytical expressions of both excess minority carrier density and photovoltage. Based on these expressions, the solar cell capacitance was calculated; we then exhibited the effects of both temperature and incidence angle on the solar cell ca...

10. The Indiana silicon sphere 4π charged-particle detector array

A low threshold charged particle detector array for the study of fragmentation processes in light-ion-induced reactions has been constructed and successfully implemented at the IUCF and Saturne II accelerators. The array consists of 162-triple-element detector telescopes mounted in a spherical geometry and covering 74% of 4π in solid angle. Telescope elements are composed of (1) an axial-field gas ionization chamber operated with C3F8 gas; (2) a 0.5 mm thick passivated silicon detector, and (3) a 2.8 cm thick CsI(Tl) scintillation crystal with photodiode readout. Discrete element identification is obtained for ejectiles up to Z similar 16 over the dynamic range 0.7≤E/A≤95 MeV/nucleon. Isotopes are also distinguished for H, He, Li and Be ejectiles with 8< or ∼E/A< or ∼95 MeV. Custom-designed electronics are employed for bias supplies and linear signal processing. Data are acquired via a CAMAC/VME/Ethernet system. (orig.)

11. The Indiana silicon sphere 4 π charged-particle detector array

Kwiatkowski, K.; Bracken, D. S.; Morley, K. B.; Brzychczyk, J.; Foxford, E. Renshaw; Komisarcik, K.; Viola, V. E.; Yoder, N. R.; Dorsett, J.; Poehlman, J.; Madden, N.; Ottarson, J.

1995-02-01

A low threshold charged particle detector array for the study of fragmentation processes in light-ion-induced reactions has been constructed and successfully implemented at the IUCF and Saturne II accelerators. The array consists of 162-triple-element detector telescopes mounted in a spherical geometry and covering 74% of 4π in solid angle. Telescope elements are composed of (1) an axial-field gas ionization chamber operated with C3F8 gas; (2) a 0.5 mm thick passivated silicon detector, and (3) a 2.8 cm thick CsI(TI) scintillation crystal with photodiode readout. Discrete element identification is obtained for ejectiles up to Z ~ 16 over the dynamic range 0.7 <= E/A <= 95 MeV/nucleon. Isotopes are also distinguished for H, He, Li and Be ejectiles with 8 <~ E/A <~ 95 MeV. Custom-designed electronics are employed for bias supplies and linear signal processing. Data are acquired via a CAMAC/VME/Ethernet system.

12. The Indiana silicon sphere 4{pi} charged-particle detector array

Kwiatkowski, K. [Indiana Univ., Bloomington, IN (United States). Dept. of Chem. and Phys. and IUCF; Bracken, D.S. [Indiana Univ., Bloomington, IN (United States). Dept. of Chem. and Phys. and IUCF; Morley, K.B. [Indiana Univ., Bloomington, IN (United States). Dept. of Chem. and Phys. and IUCF; Brzychczyk, J. [Indiana Univ., Bloomington, IN (United States). Dept. of Chem. and Phys. and IUCF; Renshaw Foxford, E. [Indiana Univ., Bloomington, IN (United States). Dept. of Chem. and Phys. and IUCF; Komisarcik, K. [Indiana Univ., Bloomington, IN (United States). Dept. of Chem. and Phys. and IUCF; Viola, V.E. [Indiana Univ., Bloomington, IN (United States). Dept. of Chem. and Phys. and IUCF; Yoder, N.R. [Indiana Univ., Bloomington, IN (United States). Dept. of Chem. and Phys. and IUCF; Dorsett, J. [Department of Chemistry Technical Services, Indiana University, Bloomington, IN 47405 (United States); Poehlman, J. [Department of Chemistry Technical Services, Indiana University, Bloomington, IN 47405 (United States); Madden, N. [Consultant, Livermore, CA (United States); Ottarson, J. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824 (United States)

1995-06-15

A low threshold charged particle detector array for the study of fragmentation processes in light-ion-induced reactions has been constructed and successfully implemented at the IUCF and Saturne II accelerators. The array consists of 162-triple-element detector telescopes mounted in a spherical geometry and covering 74% of 4{pi} in solid angle. Telescope elements are composed of (1) an axial-field gas ionization chamber operated with C{sub 3}F{sub 8} gas; (2) a 0.5 mm thick passivated silicon detector, and (3) a 2.8 cm thick CsI(Tl) scintillation crystal with photodiode readout. Discrete element identification is obtained for ejectiles up to Z similar 16 over the dynamic range 0.7{<=}E/A{<=}95 MeV/nucleon. Isotopes are also distinguished for H, He, Li and Be ejectiles with 8< or {approx}E/A< or {approx}95 MeV. Custom-designed electronics are employed for bias supplies and linear signal processing. Data are acquired via a CAMAC/VME/Ethernet system. (orig.).

13. Fluorinion transfer in silver-assisted chemical etching for silicon nanowires arrays

Feng, Tianyu; Xu, Youlong, E-mail: ylxu@mail.xjtu.edu.cn; Zhang, Zhengwei; Mao, Shengchun

2015-08-30

Graphical abstract: - Highlights: • How Ag transfers F{sup −} to the adjacent Si atom was investigated and deduced by DFT at atomic scale. • Three-electrode CV tests proved the transferring function of Ag in the etching reaction. • Uniform SiNWAs were fabricated on unpolished silicon wafers with KOH pretreatment. - Abstract: Uniform silicon nanowires arrays (SiNWAs) were fabricated on unpolished rough silicon wafers through KOH pretreatment followed by silver-assisted chemical etching (SACE). Density functional theory (DFT) calculations were used to investigate the function of silver (Ag) at atomic scale in the etching process. Among three adsorption sites of Ag atom on Si(1 0 0) surface, Ag(T4) above the fourth-layer surface Si atoms could transfer fluorinion (F{sup −}) to adjacent Si successfully due to its stronger electrostatic attraction force between Ag(T4) and F{sup −}, smaller azimuth angle of F−Ag(T4)−Si, shorter bond length of F−Si compared with F−Ag. As F{sup −} was transferred to adjacent Si by Ag(T4) one by one, the Si got away from the wafer in the form of SiF{sub 4} when it bonded with enough F{sup −} while Ag(T4) was still attached onto the Si wafer ready for next transfer. Cyclic voltammetry tests confirmed that Ag can improve the etching rate by transferring F{sup −} to Si.

14. Controlled Evolution of Silicon Nanocone Arrays Induced by Ar+ Sputtering at Room Temperature

LI Qin-Tao; LI Zhi-Gang; XIE Qiao-Ling; GONG Jin-Long; ZHU De-Zhang

2009-01-01

Controlled evolution of silicon nanocone arrays induced by Ar+ sputtering at room temperature, using the coating carbon as a mask, is demonstrated. The investigation of scanning electron microscopy indicates that the morphology of silicon nanostructures can be controlled by adjusting the thickness of the coating carbon film.Increasing the thickness of the coating carbon film from 50-6Onm, 250-300nm and 750-800nm to 150Onm, the morphologies of silicon nanostructures are transformed from smooth surface ripple, coarse surface ripple and surface ripple with densely distributed nanocones to nanocone arrays with a high density of about 1 × 109-2 × 109 cm-2.

15. Synthesize of barium ferrite nanowire array by self-fabricated porous silicon template

Zheng, Hui; Han, Mangui; Deng, Jiangxia; Zheng, Liang; Wu, Jun; Deng, Longjiang; Qin, Huibin

2014-08-01

In this work, we synthesize barium ferrite (BaFe12O19) nanowire array in porous silicon template. The porous silicon templates are prepared via gold-assisted chemical etching method. The gold (Au) nanoparticles with mean diameter of 30 nm and distance of 100 nm were ordered on the surface of Si substrate through the Polystyrene (510000)-block-poly (2-vinylpyridine) (31000) (PS510000-b-P2VP31000) diblock copolymer. Porous silicon templates with mean diameter of 500 nm and distance between the pores of 500 nm were fabricated by two etching steps. BaFe12O19 nanowires with mean diameter of 200 nm were synthesized into a porous silicon template by a sol-gel method. Magnetic hysteresis loops show an isotropic feature of the BaFe12O19 nanowires array. The coercivity (Hc) and squareness ratio (Mr/Ms) of nanowire arrays are 2560 Oe and 0.6, respectively.

16. Silicon Nanoridge Array Waveguides for Nonlinear and Sensing Applications

Puckett, Matthew W; Vallini, Felipe; Shahin, Shiva; Monifi, Faraz; Barrina, Peter N; Mehravar, Soroush; Kieu, Khanh; Fainman, Yeshaiahu

2015-01-01

We fabricate and characterize waveguides composed of closely spaced and longitudinally oriented silicon ridges etched into silicon-on-insulator wafers. Through both guided mode and bulk measurements, we demonstrate that the patterning of silicon waveguides on such a deeply subwavelength scale is desirable for nonlinear and sensing applications alike. The proposed waveguide geometry simultaneously exhibits comparable propagation loss to similar schemes proposed in literature, an enhanced effective third-order nonlinear susceptibility, and high sensitivity to perturbations in its environment.

17. Continuum framework for dislocation structure, energy and dynamics of dislocation arrays and low angle grain boundaries

Zhu, Xiaohong; Xiang, Yang

2014-09-01

We present a continuum framework for dislocation structure, energy and dynamics of dislocation arrays and low angle grain boundaries that are allowed to be nonplanar or nonequilibrium. In our continuum framework, we define a dislocation density potential function on the dislocation array surface or grain boundary to describe the orientation dependent continuous distribution of dislocations in a very simple and accurate way. The continuum formulations incorporate both the long-range dislocation interaction and the local dislocation line energy, and are derived from the discrete dislocation model. The continuum framework recovers the classical Read-Shockley energy formula when the long-range elastic fields of the low angle grain boundaries are canceled out. Applications of our continuum framework in this paper are focused on dislocation structures on static planar and nonplanar low angle grain boundaries and misfitting interfaces. We present two methods under our continuum framework for this purpose, including the method based on the Franks formula and the energy minimization method. We show that for any (planar or nonplanar) low angle grain boundary, the Franks formula holds if and only if the long-range stress field in the continuum model is canceled out, and it does not necessarily hold for a total energy minimum dislocation structure.

18. Field Emission from Amorphous carbon Nitride Films Deposited on silicon Tip Arrays

李俊杰; 郑伟涛; 孙龙; 卞海蛟; 金曾孙; 赵海峰; 宋航; 孟松鹤; 赫晓东; 韩杰才

2003-01-01

Amorphous carbon nitride films (a-CNx) were deposited on silicon tip arrays by rf magnetron sputtering in pure nitrogen atmosphere. The field emission property of carbon nitride films on Si tips was compared with that of carbon nitride on silicon wafer. The results show that field emission property of carbon nitride films deposited on silicon tips can be improved significantly in contrast with that on wafer. It can be explained that field emission is sensitive to the local curvature and geometry, thus silicon tips can effectively promote field emission property of a-CNx films. In addition, the films deposited on silicon tips have a smaller effective work function ( F = 0.024 eV)of electron field emission than that on silicon wafer ( F = 0.060 e V), which indicates a significant enhancement of the ability of electron field emission from a-CNx films.

19. Beam Tilt-Angle Estimation for Monopole End-Fire Array Mounted on a Finite Ground Plane

Jia Cao; Zhenghui Xue; Meng Cao

2015-01-01

A modified method for the beam tilt-angle estimation of monopole end-fire array mounted on finite ground plane is proposed. In the simplified model, the monopole array and ground plane are approximated to two line sources of transverse and longitudinal electric current, respectively. It is deduced that the beam tilt angle is a function about the length of ground plane in front of array Lg, the length of monopole array La, and the phase constant βα. After verifying the optimizing principle of ...

20. W-band Phased Array Systems using Silicon Integrated Circuits

Kim, Sang Young

This thesis presents the silicon-based on-chip W-band phased array systems. An improved quadrature all-pass filter (QAF) and its implementation in 60--80 GHz active phase shifter using 0.13 microm SiGe BiCMOS technology is presented. It is demonstrated that with the inclusion of an Rs/R in the high Q branches of C and L, the sensitivity to the loading capacitance, therefore the I/Q phase and amplitude errors are minimized. This technique is especially suited for wideband millimeter-wave circuits where the loading capacitance (CL) is comparable to the filter capacitance (C). A prototype 60--80 GHz active phased shifter using the improved QAF is demonstrated. The overall chip size is 1.15 x 0.92 mm2 with the power consumption of 108 mW. The measured S11 and S22 are switches is demonstrated. The phase shifter is based on a low-pass pi-network. The chip size is 0.45 x 0.3 mm2 without pads and consumes virtually no power. The measured S11 and S22 is 8 dBm and the simulated IIP3 is > 22 dBm. A low-power 76--84 GHz 4-element phased array receiver using the designed passive phase shifter is presented. The power consumption is minimized by using a single-ended design and alternating the amplifiers and phase shifter cells to result in a low noise figure at a low power consumption. A variable gain amplifier and the 11° phase shifter are used to correct for the rms gain and phase errors at different operating frequencies. The overall chip size is 2.0 x 2.7 mm2 with the current consumption of 18 mA/channel with 1.8 V supply voltage. The measured S11 and S 22 is chip coupling is circuits are designed differentially to result in less sensitivity to packaging effect and high channel-to-channel isolation. The overall chip size is 5.0 x 5.8 mm 2 with the power consumption of 500--600 mA from 2 V supply voltage. The measured S11 and S22 for all 16 phase states is 10 dB for 76.4--90 GHz with the rms gain error of -45 dB. The measured NF is 11.2--13 dB at 77--87 GHz at the maximum

1. Structure and field emission of graphene layers on top of silicon nanowire arrays

Huang, Bohr-Ran; Chan, Hui-Wen; Jou, Shyankay; Chen, Guan-Yu; Kuo, Hsiu-An; Song, Wan-Jhen

2016-01-01

Monolayer graphene was grown on copper foils and then transferred on planar silicon substrates and on top of silicon nanowire (SiNW) arrays to form single- to quadruple-layer graphene films. The morphology, structure, and electron field emission (FE) of these graphene films were investigated. The graphene films on the planar silicon substrates were continuous. The single- to triple-layer graphene films on the SiNW arrays were discontinuous and while the quadruple-layer graphene film featured a mostly continuous area. The Raman spectra of the graphene films on the SiNW arrays showed G and Gʹ bands with a singular-Lorentzian shape together with a weak D band. The D band intensity decreased as the number of graphene layers increased. The FE efficiency of the graphene films on the planar silicon substrates and the SiNW arrays varied with the number of graphene layers. The turn-on field for the single- to quadruple-layer graphene films on planar silicon substrates were 4.3, 3.7, 3.5 and 3.4 V/μm, respectively. The turn-on field for the single- to quadruple-layer graphene films on SiNW arrays decreased to 3.9, 3.3, 3.0 and 3.3 V/μm, respectively. Correlation of the FE with structure and morphology of the graphene films is discussed.

2. Dependence of the output parameters of the polycrystalline silicon (cast) solar cell on the incident radiation angle

The decrease in output parameters of polycrystalline silicon (CAST) solar cells with increasing angle of incidence has been investigated. The distribution of the surface photon, reflection losses and effective junction depth are modeled, by taking in the front surface recombination velocity< It is shown that that angle of incidence radiation is depended on the increase of the surface recombination velocity.(Author)

3. Micro-Textured Black Silicon Wick for Silicon Heat Pipe Array

Yee, Karl Y.; Sunada, Eric T.; Ganapathi, Gani B.; Manohara, Harish; Homyk, Andrew; Prina, Mauro

2013-01-01

Planar, semiconductor heat arrays have been previously proposed and developed; however, this design makes use of a novel, microscale black silicon wick structure that provides increased capillary pumping pressure of the internal working fluid, resulting in increased effective thermal conductivity of the device, and also enables operation of the device in any orientation with respect to the gravity vector. In a heat pipe, the efficiency of thermal transfer from the case to the working fluid is directly proportional to the surface area of the wick in contact with the fluid. Also, the primary failure mechanism for heat pipes operating within the temperature range of interest is inadequate capillary pressure for the return of fluid from the condenser to the wick. This is also what makes the operation of heat pipes orientation-sensitive. Thus, the two primary requirements for a good wick design are a large surface area and high capillary pressure. Surface area can be maximized through nanomachined surface roughening. Capillary pressure is largely driven by the working fluid and wick structure. The proposed nanostructure wick has characteristic dimensions on the order of tens of microns, which promotes menisci of very small radii. This results in the possibility of enormous pumping potential due to the inverse proportionality with radius. Wetting, which also enhances capillary pumping, can be maximized through growth of an oxide layer or material deposition (e.g. TiO2) to create a superhydrophilic surface.

4. Small-angle scatter tomography with a photon-counting detector array

Pang, Shuo; Zhu, Zheyuan; Wang, Ge; Cong, Wenxiang

2016-05-01

Small-angle x-ray scatter imaging has a high intrinsic contrast in cancer research and other applications, and provides information on molecular composition and micro-structure of the tissue. In general, the implementations of small-angle coherent scatter imaging can be divided into two main categories: direct tomography and angular dispersive computerized tomography. Based on the recent development of energy-discriminative photon-counting detector array, here we propose a computerized tomography setup based on energy-dispersive measurement with a photon-counting detector array. To show merits of the energy-dispersive approach, we have performed numerical tests with a phantom containing various tissue types, in comparison with the existing imaging approaches. The results show that with an energy resolution of ~6 keV, the energy dispersive tomography system with a broadband tabletop x-ray would outperform the angular dispersive system, which makes the x-ray small-angle scatter tomography promising for high-specificity tissue imaging.

5. Optical absorption enhancement in submicrometre crystalline silicon films with nanotexturing arrays for solar photovoltaic applications

Optical absorption enhancement in submicrometre silicon films with three types of nanotexturing arrays, i.e. a column-shaped nanohole (CLNH), and a cone-shaped nanohole (CNNH) and an inverted cone-shaped nanohole (I-CNNH) array, is studied via simulation. The ultimate efficiency, which is a function of the type of array, film thickness, array period and filling fraction, is optimized. We find that in all the CNNH (or I-CNNH) arrays with the same film thickness and the same period, the ones having a filling fraction equal to the critical value of 1 − π/12 correspond to the highest ultimate efficiencies. For a given type of array and film thickness, the ultimate efficiency is optimized over the array period and filling fraction, which is defined as the optimized ultimate efficiency (OUE). In the three types of nanotextured silicon films with the same thickness in the range 250–2000 nm, the CNNH arrays show the highest optimized ultimate efficiency (OUE); however, the CLNH arrays show the highest OUEs when the film thickness is equal to 125 and 62.5 nm, and when the film thickness is in the range 500–2000 nm, the I-CNNH arrays show the lowest OUEs. The OUEs of 250 nm, 500 nm, 1000 nm and 2000 nm thick CNNH array textured silicon films are 19.88%, 28.51%, 34.06% and 39.53%, respectively. For the CNNH array, when the film thickness is reduced from 2000 nm to one-eighth, the OUE is only reduced to half its value. (paper)

6. Dynamic Conformations of Nucleosome Arrays in Solution from Small-Angle X-ray Scattering

Howell, Steven C.

Chromatin conformation and dynamics remains unsolved despite the critical role of the chromatin in fundamental genetic functions such as transcription, replication, and repair. At the molecular level, chromatin can be viewed as a linear array of nucleosomes, each consisting of 147 base pairs (bp) of double-stranded DNA (dsDNA) wrapped around a protein core and connected by 10 to 90 bp of linker dsDNA. Using small-angle X-ray scattering (SAXS), we investigated how the conformations of model nucleosome arrays in solution are modulated by ionic condition as well as the effect of linker histone proteins. To facilitate ensemble modeling of these SAXS measurements, we developed a simulation method that treats coarse-grained DNA as a Markov chain, then explores possible DNA conformations using Metropolis Monte Carlo (MC) sampling. This algorithm extends the functionality of SASSIE, a program used to model intrinsically disordered biological molecules, adding to the previous methods for simulating protein, carbohydrates, and single-stranded DNA. Our SAXS measurements of various nucleosome arrays together with the MC generated models provide valuable solution structure information identifying specific differences from the structure of crystallized arrays.

7. Design of a silicon avalanche photodiode pixel with integrated laser diode using back-illuminated crystallographically etched silicon-on-sapphire with monolithically integrated microlens for dual-mode passive and active imaging arrays

Stern, Alvin G.

2010-08-01

There is a growing need in scientific research applications for dual-mode, passive and active 2D and 3D LADAR imaging methods. To fill this need, an advanced back-illuminated silicon avalanche photodiode (APD) design is presented using a novel silicon-on-sapphire substrate incorporating a crystalline aluminum nitride (AlN) antireflective layer between the silicon and R-plane sapphire. This allows integration of a high quantum efficiency silicon APD with a gallium nitride (GaN) laser diode in each pixel. The pixel design enables single photon sensitive, solid-state focal plane arrays (FPAs) with wide dynamic range, supporting passive and active imaging capability in a single FPA. When (100) silicon is properly etched with TMAH solution, square based pyramidal frustum or mesa arrays result with the four mesa sidewalls of the APD formed by (111) silicon planes that intersect the (100) planes at a crystallographic angle, φ c = 54.7°. The APD device is fabricated in the mesa using conventional silicon processing technology. The GaN laser diode is fabricated by epitaxial growth inside of an inverted, etched cavity in the silicon mesa. Microlenses are fabricated in the thinned, and AR-coated sapphire substrate. The APDs share a common, front-side anode contact, and laser diodes share a common cathode. A low resistance (Al) or (Cu) metal anode grid fills the space between pixels and also inhibits optical crosstalk. SOS-APD arrays are flip-chip bump-bonded to CMOS readout ICs to produce hybrid FPAs. The square 27 μm emitter-detector pixel achieves SNR > 1 in active detection mode for Lambert surfaces at 1,000 meters.

8. A floating 3D silicon microprobe array for neural drug delivery compatible with electrical recording

This paper reports on the design, fabrication, assembly and characterization of a three-dimensional silicon-based floating microprobe array for localized drug delivery to be applied in neuroscience research. The microprobe array is composed of a silicon platform into which up to four silicon probe combs with needle-like probe shafts can be inserted. Two dedicated positions in the array allow the integration of combs for drug delivery. The implemented comb variants feature 8 mm long probe shafts with two individually addressable microchannels incorporated in a single shaft or distributed to two shafts. Liquid supply to the array is realized by a highly flexible 250 µm thick multi-lumen microfluidic cable made from polydimethylsiloxane (PDMS). The specific design concept of the slim-base platform enables floating implantation of the array in the small space between brain and skull. In turn, the flexible cable mechanically decouples the array from any microfluidic interface rigidly fixed to the skull. After assembly of the array, full functionality is demonstrated and characterized at infusion rates from 1 to 5 µL min−1. Further, the effect of a parylene-C coating on the water vapour and osmotic liquid water transport through the PDMS cable walls is experimentally evaluated by determining the respective transmission rates including the water vapour permeability of the used PDMS type.

9. Periodic nano/micro-hole array silicon solar cell

Lai, Guan-Yu; Kumar, Dinesh P; Pei, Zingway

2014-01-01

In this study, we applied a metal catalyst etching method to fabricate a nano/microhole array on a Si substrate for application in solar cells. In addition, the surface of an undesigned area was etched because of the attachment of metal nanoparticles that is dissociated in a solution. The nano/microhole array exhibited low specular reflectance (

10. Dense nanoimprinted silicon nanowire arrays with passivated axial p-i-n junctions for photovoltaic applications

Zhang, Peng; Liu, Pei; Siontas, Stylianos; Zaslavsky, A.; Pacifici, D.; Ha, Jong-Yoon; Krylyuk, S.; Davydov, A. V.

2015-03-01

We report on the fabrication and photovoltaic characteristics of vertical arrays of silicon axial p-i-n junction nanowire (NW) solar cells grown by vapor-liquid-solid (VLS) epitaxy. NW surface passivation with silicon dioxide shell is shown to enhance carrier recombination time, open-circuit voltage (VOC), short-circuit current density (JSC), and fill factor (FF). The photovoltaic performance of passivated individual NW and NW arrays was compared under 532 nm laser illumination with power density of ˜10 W/cm2. Higher values of VOC and FF in the NW arrays are explained by enhanced light trapping. In order to verify the effect of NW density on light absorption and hence on the photovoltaic performance of NW arrays, dense Si NW arrays were fabricated using nanoimprint lithography to periodically arrange the gold seed particles prior to epitaxial growth. Compared to sparse NW arrays fabricated using VLS growth from randomly distributed gold seeds, the nanoimprinted NW array solar cells show a greatly increased peak external quantum efficiency of ˜8% and internal quantum efficiency of ˜90% in the visible spectral range. Three-dimensional finite-difference time-domain simulations of Si NW periodic arrays with varying pitch (P) confirm the importance of high NW density. Specifically, due to diffractive scattering and light trapping, absorption efficiency close to 100% in the 400-650 nm spectral range is calculated for a Si NW array with P = 250 nm, significantly outperforming a blanket Si film of the same thickness.

11. Automatic Release of Silicon Nanowire Arrays with a High Integrity for Flexible Electronic Devices

Luo Wu; Shuxin Li; Weiwei He; Dayong Teng; Ke Wang; Changhui Ye

2014-01-01

Automatic release and vertical transferring of silicon/silicon oxide nanowire arrays with a high integrity are demonstrated by an Ag-assisted ammonia etching method. By adding a water steaming step between Ag-assisted HF/H2O2 and ammonia etching to form a SiOx protective layer sheathing Si nanowires, we can tune the composition of the nanowires from SiOx (0 ≤ x ≤ 2) to Si nanowires. Ag plays a key role to the neat and uniform release of Si/SiOx nanowire arrays from Si wafer in the ammonia etc...

12. Amorphous silicon sensor arrays for X-ray and document imaging

Large area amorphous silicon image sensor arrays are important for X-ray medical imaging and document scanning as well as a variety of other applications where large sensor size is required. The paper first summarizes the present state of the flat panel X-ray imager technology, and compares the two main approaches for X-ray detection. The authors then describe the performance of a new, large area, high resolution, radiographic imager based o a single amorphous silicon array with 2,304 x 3,200 pixels, and an active area of 30 x 40 cm (12 x 16 inches)

13. Efficiency improvement of silicon solar cells enabled by ZnO nanowhisker array coating

Yu, Xuegong; Wang, Dong; Lei, Dong; Li, Genhu; Yang, Deren

2012-01-01

An efficient antireflection coating is critical for the improvement of silicon solar cell performance via increased light coupling. Here, we have grown well-aligned ZnO nanowhisker (NW) arrays on Czochralski silicon solar cells by a seeding-growth two-step process. It is found that the ZnO NWs have a great effect on the macroscopic antireflection effect and, therefore, improves the solar cell performance. The ZnO NW array-coated solar cells display a broadband reflection suppression from 500 ...

14. Large scale low cost fabrication of diameter controllable silicon nanowire arrays

We report on a novel solution etching method to fabricate vertically aligned aperiodic silicon nanowire (SiNW) arrays. We begin with a simple dewetting process to fabricate a monolayer of well-spaced metal particles in situ on a silicon wafer. The particles function as a sacrificial template to pattern a Ti/Au catalyst film into a metal mesh and the size of particles directly determines the diameter of SiNW. A conventional metal-assisted chemical etching process is then carried out with the obtained metal mesh as a catalyst to realize a vertically aligned SiNW array at a large scale and low cost. (papers)

15. Fully integrated hybrid silicon free-space beam steering source with 32-channel phased array

Hulme, J. C.; Doylend, J. K.; Heck, M. J. R.; Peters, J. D.; Davenport, M. L.; Bovington, J. T.; Coldren, L. A.; Bowers, J. E.

2014-03-01

Free-space beam steering using optical phased arrays is a promising method for implementing free-space communication links and Light Detection and Ranging (LIDAR) without the sensitivity to inertial forces and long latencies which characterize moving parts. Implementing this approach on a silicon-based photonic integrated circuit adds the additional advantage of working with highly developed CMOS processing techniques. In this work we discuss our progress in the development of a fully integrated 32 channel PIC with a widely tunable diode laser, a waveguide phased array, an array of fast phase modulators, an array of hybrid III-V/silicon amplifiers, surface gratings, and a graded index lens (GRIN) feeding an array of photodiodes for feedback control. The PIC has been designed to provide beam steering across a 15°x5° field of view with 0.6°x0.6° beam width and background peaks suppressed 15 dB relative to the main lobe within the field of view for arbitrarily chosen beam directions. Fabrication follows the hybrid silicon process developed at UCSB with modifications to incorporate silicon diodes and a GRIN lens.

16. Laser desorption ionization and peptide sequencing on laser induced silicon microcolumn arrays

Vertes, Akos; Chen, Yong

2011-12-27

The present invention provides a method of producing a laser-patterned silicon surface, especially silicon wafers for use in laser desorption ionization (LDI-MS) (including MALDI-MS and SELDI-MS), devices containing the same, and methods of testing samples employing the same. The surface is prepared by subjecting a silicon substrate to multiple laser shots from a high-power picosecond or femtosecond laser while in a processing environment, e.g., underwater, and generates a remarkable homogenous microcolumn array capable of providing an improved substrate for LDI-MS.

17. Highly efficient ultrathin-film amorphous silicon solar cells on top of imprinted periodic nanodot arrays

Yan, Wensheng, E-mail: yws118@gmail.com; Gu, Min, E-mail: mgu@swin.edu.au [Centre for Micro-Photonics, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, Victoria 3122 (Australia); Tao, Zhikuo [College of Electronic Science and Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210023 (China); Ong, Thiam Min Brian [Plasma Sources and Application Center, NIE, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616 (Singapore); Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602 (Singapore)

2015-03-02

The addressing of the light absorption and conversion efficiency is critical to the ultrathin-film hydrogenated amorphous silicon (a-Si:H) solar cells. We systematically investigate ultrathin a-Si:H solar cells with a 100 nm absorber on top of imprinted hexagonal nanodot arrays. Experimental evidences are demonstrated for not only notable silver nanodot arrays but also lower-cost ITO and Al:ZnO nanodot arrays. The measured external quantum efficiency is explained by the simulation results. The J{sub sc} values are 12.1, 13.0, and 14.3 mA/cm{sup 2} and efficiencies are 6.6%, 7.5%, and 8.3% for ITO, Al:ZnO, and silver nanodot arrays, respectively. Simulated optical absorption distribution shows high light trapping within amorphous silicon layer.

18. Automatic Release of Silicon Nanowire Arrays with a High Integrity for Flexible Electronic Devices

Wu, Luo; Li, Shuxin; He, Weiwei; Teng, Dayong; Wang, Ke; Ye, Changhui

2014-01-01

Automatic release and vertical transferring of silicon/silicon oxide nanowire arrays with a high integrity are demonstrated by an Ag-assisted ammonia etching method. By adding a water steaming step between Ag-assisted HF/H2O2 and ammonia etching to form a SiOx protective layer sheathing Si nanowires, we can tune the composition of the nanowires from SiOx (0 ≤ x ≤ 2) to Si nanowires. Ag plays a key role to the neat and uniform release of Si/SiOx nanowire arrays from Si wafer in the ammonia etching process. The vertical Si nanowire array device, with both sides having high-quality Ohmic contact, can be transferred to arbitrary substrates, especially on a flexible substrate. The method developed here offers a facile method to realize flexible Si nanowire array functional devices. PMID:24487460

19. Automatic release of silicon nanowire arrays with a high integrity for flexible electronic devices.

Wu, Luo; Li, Shuxin; He, Weiwei; Teng, Dayong; Wang, Ke; Ye, Changhui

2014-01-01

Automatic release and vertical transferring of silicon/silicon oxide nanowire arrays with a high integrity are demonstrated by an Ag-assisted ammonia etching method. By adding a water steaming step between Ag-assisted HF/H2O2 and ammonia etching to form a SiOx protective layer sheathing Si nanowires, we can tune the composition of the nanowires from SiOx (0 ≤ x ≤ 2) to Si nanowires. Ag plays a key role to the neat and uniform release of Si/SiOx nanowire arrays from Si wafer in the ammonia etching process. The vertical Si nanowire array device, with both sides having high-quality Ohmic contact, can be transferred to arbitrary substrates, especially on a flexible substrate. The method developed here offers a facile method to realize flexible Si nanowire array functional devices. PMID:24487460

20. Highly efficient ultrathin-film amorphous silicon solar cells on top of imprinted periodic nanodot arrays

The addressing of the light absorption and conversion efficiency is critical to the ultrathin-film hydrogenated amorphous silicon (a-Si:H) solar cells. We systematically investigate ultrathin a-Si:H solar cells with a 100 nm absorber on top of imprinted hexagonal nanodot arrays. Experimental evidences are demonstrated for not only notable silver nanodot arrays but also lower-cost ITO and Al:ZnO nanodot arrays. The measured external quantum efficiency is explained by the simulation results. The Jsc values are 12.1, 13.0, and 14.3 mA/cm2 and efficiencies are 6.6%, 7.5%, and 8.3% for ITO, Al:ZnO, and silver nanodot arrays, respectively. Simulated optical absorption distribution shows high light trapping within amorphous silicon layer

1. Silicon nanowire arrays coupled with cobalt phosphide spheres as low-cost photocathodes for efficient solar hydrogen evolution.

Bao, Xiao-Qing; Fatima Cerqueira, M; Alpuim, Pedro; Liu, Lifeng

2015-07-01

We demonstrate the first example of silicon nanowire array photocathodes coupled with hollow spheres of the emerging earth-abundant cobalt phosphide catalysts. Compared to bare silicon nanowire arrays, the hybrid electrodes exhibit significantly improved photoelectrochemical performance toward the solar-driven H2 evolution reaction. PMID:26050844

2. Silicon nanowire arrays coupled with cobalt phosphide spheres as low-cost photocathodes for efficient solar hydrogen evolution

Bao, Xiao-Qing; Cerqueira, M. F.; Alpuim, P.; Liu, Lifeng

2015-01-01

We demonstrate the first example of silicon nanowire array photocathodes coupled with hollow spheres of the emerging earth-abundant cobalt phosphide catalysts. Compared to bare silicon nanowire arrays, the hybrid electrodes exhibit significantly improved photoelectrochemical performance toward the solar-driven H2 evolution reaction.

3. Fabrication of porous silicon by metal-assisted etching using highly ordered gold nanoparticle arrays

Scheeler, Sebastian P; Ullrich, Simon; Kudera, Stefan; Pacholski, Claudia

2012-01-01

A simple method for the fabrication of porous silicon (Si) by metal-assisted etching was developed using gold nanoparticles as catalytic sites. The etching masks were prepared by spin-coating of colloidal gold nanoparticles onto Si. An appropriate functionalization of the gold nanoparticle surface prior to the deposition step enabled the formation of quasi-hexagonally ordered arrays by self-assembly which were translated into an array of pores by subsequent etching in HF solution containing H...

4. Design and test of reliable high strength ingressive polycrystalline silicon microgripper arrays

We present the design and validation of a micromachined gripper array that enables reliable transmission of forces of at least 14 mN. The gripper is constructed with polycrystalline silicon (polysilicon), a brittle material, and is compatible with polysilicon surface micromachining. Two ingressive snap-and-lock array designs are presented. After developing design guidelines, it is shown that the first gripper array is functional. However, a risk remains that the gripper array rather than the tensile bar that it grips in its intended application fails. Therefore, an improved geometry is designed and it is shown that it is robust with respect to failure. Scanning confocal Raman imaging directly confirms that the local peak tensile stresses in the robust gripper array are approximately 50% of the lower bound material strength, and also resolves a 25% stress variation across the array. (paper)

5. Design and test of reliable high strength ingressive polycrystalline silicon microgripper arrays

Hazra, S. S.; Beuth, J. L.; Myers, G. A.; DelRio, F. W.; de Boer, M. P.

2015-01-01

We present the design and validation of a micromachined gripper array that enables reliable transmission of forces of at least 14 mN. The gripper is constructed with polycrystalline silicon (polysilicon), a brittle material, and is compatible with polysilicon surface micromachining. Two ingressive snap-and-lock array designs are presented. After developing design guidelines, it is shown that the first gripper array is functional. However, a risk remains that the gripper array rather than the tensile bar that it grips in its intended application fails. Therefore, an improved geometry is designed and it is shown that it is robust with respect to failure. Scanning confocal Raman imaging directly confirms that the local peak tensile stresses in the robust gripper array are approximately 50% of the lower bound material strength, and also resolves a 25% stress variation across the array.

6. Rice-straw-like structure of silicon nanowire arrays for a hydrogen gas sensor

A rice-straw-like silicon nanowire (SiNW) array was developed for hydrogen gas sensing applications. The straight-aligned SiNW array sensor was first fabricated by the metal-assisted electroless etching (MAEE) technique. Rice-straw-like SiNW arrays were formed using a repeated MAEE technique. Hydrogen sensing characteristics were measured for gas concentrations from 20 to 1000 ppm at room temperature. The rice-straw-like SiNW-array-based hydrogen gas sensor performed with low noise and a high response (232.5%) for 1000 ppm hydrogen gas. It was found that the rice-straw-like SiNW-array hydrogen gas sensor had a much better response (approximately 2.5 times) than the straight-aligned SiNW-array sensor. The rice-straw-like SiNW-array structure effectively increased the surface area and the concentration of silicon oxide, which provided additional binding sites for gas molecules. Thus, the rice-straw-like SiNW-array-based hydrogen gas sensor possessed good sensing properties and has the potential for mass production of sensing devices. (paper)

7. Wide-angle antireflection ZnO films on bullet-like nanostructures of multi-crystalline silicon

Nanosphere lithography and antireflection coating techniques have been applied to fabricate wide-angle antireflection structures on multicrystalline silicon substrates. Self-assembled 550-nm SiO2 nanospheres were arranged periodically to act as a mask to block the inductively coupled plasma dry etching and form bulletlike nanostructures on the surface of the multicrystalline silicon wafer. Then a 65-nm-thick zinc oxide film was deposited on the nanostructures using the atomic layer deposition method. The results show that when applying the nanostructure with a ZnO film the average reflectivity of the multicrystalline silicon wafer can be decreased from 36% to 0.65% in the wavelength range from 400 nm to 850 nm for an incident angle of 8 deg. . When the incident angle reaches 60 deg. the average reflectivity of the sample becomes less than 4.6%.

8. Fabrication of Large-Area Hierarchical Structure Array Using Siliconized-Silsesquioxane as a Nanoscale Etching Barrier.

Lee, Bong Kuk; Baek, In-Bok; Kim, Yarkyeon; Jang, Won Ick; Yoon, Yong Sun; Yu, Han Young

2015-06-24

A material approach to fabricate a large-area hierarchical structure array is presented. The replica molding and oxygen (O2) plasma etching processes were combined to fabricate a large-area hierarchical structure array. Liquid blends consisting of siliconized silsesquioxane acrylate (Si-SSQA), ethylene glycol dimethacrylate (EGDMA), and photoinitiator are developed as a roughness amplifying material during O2 plasma etching. Microstructures composed of the Si-SSQA/EGDMA mixtures are fabricated by replica molding. Nanoscale roughness on molded microstructures is realized by O2 etching. The nanoscale roughness on microstructures is efficiently controlled by varying the etching time and the weight ratio of Si-SSQA to EGDMA. The hierarchical structures fabricated by combining replica molding and O2 plasma etching showed superhydrophilicity with long-term stability, resulting in the formation of hydroxyl-terminated silicon oxide layer with the reorientation limit. On the other hand, the hierarchical structures modified with a perfluorinated monolayer showed superhydrophobicity. The increment of water contact angles is consistent with increment of the nano/microroughness of hierarchical structures and decrement of the top contact area of water/hierarchical structures. PMID:26047057

9. The automated array assembly task of the low-cost silicon solar array project, phase 2

Coleman, M. G.; Pryor, R. A.; Sparks, T. G.; Legge, R.; Saltzman, D. L.

1980-01-01

Several specific processing steps as part of a total process sequence for manufacturing silicon solar cells were studied. Ion implantation was identified as the preferred process step for impurity doping. Unanalyzed beam ion implantation was shown to have major cost advantages over analyzed beam implantation. Further, high quality cells were fabricated using a high current unanalyzed beam. Mechanically masked plasma patterning of silicon nitride was shown to be capable of forming fine lines on silicon surfaces with spacings between mask and substrate as great as 250 micrometers. Extensive work was performed on advances in plated metallization. The need for the thick electroless palladium layer was eliminated. Further, copper was successfully utilized as a conductor layer utilizing nickel as a barrier to copper diffusion into the silicon. Plasma etching of silicon for texturing and saw damage removal was shown technically feasible but not cost effective compared to wet chemical etching techniques.

Heij, W. de; Boer, A. de; Hek, A.P. de; Vliet, F.E. van

2011-01-01

A Silicon-Germanium single chip receiver has been developed for S-band phased array radars with 2-D digital beamforming. The complete receiver chain from the S-band RF input up to the low-IF output has been integrated on a single SiGe chip. The only external components required to complete the recei

11. Performance of a TiN-coated monolithic silicon pin-diode array under mechanical stress

VanDevender, B A; Myers, A W; Amsbaugh, J F; Howe, M A; Leber, M L; Robertson, R G H; Tolich, K; Van Wechel, T D; Wall, B L; 10.1016/j.nima.2012.01.033

2012-01-01

The Karlsruhe Tritium Neutrino Experiment (KATRIN) will detect tritium beta- decay electrons that pass through its electromagnetic spectrometer with a highly- segmented monolithic silicon pin-diode focal-plane detector (FPD). This pin-diode array will be on a single piece of 500-{\\mu}m-thick silicon, with contact between titanium nitride (TiN) coated detector pixels and front-end electronics made by spring-loaded pogo pins. The pogo pins will exert a total force of up to 50N on the detector, deforming it and resulting in mechanical stress up to 50 MPa in the silicon bulk. We have evaluated a prototype pin-diode array with a pogo-pin connection scheme similar to the KATRIN FPD. We find that pogo pins make good electrical contact to TiN and observe no effects on detector resolution or reverse-bias leakage current which can be attributed to mechanical stress.

12. Ordered arrays of embedded Ga nanoparticles on patterned silicon substrates

We fabricate site-controlled, ordered arrays of embedded Ga nanoparticles on Si, using a combination of substrate patterning and molecular-beam epitaxial growth. The fabrication process consists of two steps. Ga droplets are initially nucleated in an ordered array of inverted pyramidal pits, and then partially crystallized by exposure to an As flux, which promotes the formation of a GaAs shell that seals the Ga nanoparticle within two semiconductor layers. The nanoparticle formation process has been investigated through a combination of extensive chemical and structural characterization and theoretical kinetic Monte Carlo simulations. (papers)

13. Ordered arrays of embedded Ga nanoparticles on patterned silicon substrates.

Bollani, M; Bietti, S; Frigeri, C; Chrastina, D; Reyes, K; Smereka, P; Millunchick, J M; Vanacore, G M; Burghammer, M; Tagliaferri, A; Sanguinetti, S

2014-05-23

We fabricate site-controlled, ordered arrays of embedded Ga nanoparticles on Si, using a combination of substrate patterning and molecular-beam epitaxial growth. The fabrication process consists of two steps. Ga droplets are initially nucleated in an ordered array of inverted pyramidal pits, and then partially crystallized by exposure to an As flux, which promotes the formation of a GaAs shell that seals the Ga nanoparticle within two semiconductor layers. The nanoparticle formation process has been investigated through a combination of extensive chemical and structural characterization and theoretical kinetic Monte Carlo simulations. PMID:24784353

14. Materials preparation and fabrication of pyroelectric polymer/silicon MOSFET detector arrays. Final report

The authors have delivered several 64-element linear arrays of pyroelectric elements fully integrated on silicon wafers with MOS readout devices. They have delivered detailed drawings of the linear arrays to LANL. They have processed a series of two inch wafers per submitted design. Each two inch wafer contains two 64 element arrays. After spin-coating copolymer onto the arrays, vacuum depositing the top electrodes, and polarizing the copolymer films so as to make them pyroelectrically active, each wafer was split in half. The authors developed a thicker oxide coating separating the extended gate electrode (beneath the polymer detector) from the silicon. This should reduce its parasitic capacitance and hence improve the S/N. They provided LANL three processed 64 element sensor arrays. Each array was affixed to a connector panel and selected solder pads of the common ground, the common source voltage supply connections, the 64 individual drain connections, and the 64 drain connections (for direct pyroelectric sensing response rather than the MOSFET action) were wire bonded to the connector panel solder pads. This entails (64 + 64 + 1 + 1) = 130 possible bond connections per 64 element array. This report now details the processing steps and the progress of the individual wafers as they were carried through from beginning to end

15. A micromachined silicon parallel acoustic delay line (PADL) array for real-time photoacoustic tomography (PAT)

Cho, Young Y.; Chang, Cheng-Chung; Wang, Lihong V.; Zou, Jun

2015-03-01

16. Photonic light trapping in silicon nanowire arrays: deriving and overcoming the physical limitations

Schmitt, Sebastian W

2016-01-01

Hexagonally aligned, free-standing silicon nanowire (SiNW) arrays serve as photonic resonators which, as compared to a silicon (Si) thin film, do not only absorb more visible (VIS) and near-infrared (NIR) light, but also show an inherent photonic light concentration that enhances their performance as solar absorbers. Using numerical simulations we show, how light concentration is induced by high optical cross sections of the individual SiNWs but cannot be optimized independently of the SiNW array absorption. While an ideal spatial density exists, for which the SiNW array absorption for VIS and NIR wavelengths reaches a maximum, the spatial correlation of SiNWs in an array suppresses the formation of optical Mie modes responsible for light concentration. We show that different from SiNWs with straight sidewalls, arrays of inverted silicon nanocones (SiNCs) permit to avoid the mode suppression. In fact they give rise to an altered set of photonic modes which is induced by the spatial correlation of SiNCs in the...

17. Surface second harmonic generation from silicon pillar arrays with strong geometrical dependence.

Choudhury, B Dev; Sahoo, Pankaj K; Sanatinia, R; Andler, Guillermo; Anand, S; Swillo, M

2015-05-01

We present experimental demonstration and analysis of enhanced surface second harmonic generation (SHG) from hexagonal arrays of silicon pillars. Three sets of Si pillar samples with truncated cone-shaped pillar arrays having periods of 500, 1000, and 2000 nm, and corresponding average diameters of 200, 585 and 1550 nm, respectively, are fabricated by colloidal lithography and plasma dry etching. We have observed strong dependence of SHG intensity on the pillar geometry. Pillar arrays with a 1000 nm period and a 585 nm average diameter give more than a one order of magnitude higher SHG signal compared to the other two samples. We theoretically verified the dependence of SHG intensity on pillar geometry by finite difference time domain simulations in terms of the surface normal E-field component. The enhanced surface SHG light can be useful for nonlinear silicon photonics, surface/interface characterization, and optical biosensing. PMID:25927787

18. Gamma-ray imaging detectors based on silicon drift detectors arrays coupled to a single scintillator

Arrays of Silicon Drift Detectors (SDDs) coupled to a single scintillator, according to the Anger Camera scheme, can be successfully employed in gamma-ray imaging. The low value of output capacitance of a SDD allows to reach a lower electronics noise with respect to conventional silicon photodiodes used in scintillation detection. A small prototype of gamma camera with sub-millimeter resolution has been realized by using a monolithic array of small SDDs (5 mm2 each unit) with on-chip JFET. For the realization of gamma cameras of larger areas based on single units assembled in array, SDDs of 30 mm2 of area with external JFET have been also experimented

19. Phonon processes in vertically aligned silicon nanowire arrays produced by low-cost all-solution galvanic displacement method

Banerjee, Debika; Trudeau, Charles; Gerlein, Luis Felipe; Cloutier, Sylvain G.

2016-03-01

The nanoscale engineering of silicon can significantly change its bulk optoelectronic properties to make it more favorable for device integration. Phonon process engineering is one way to enhance inter-band transitions in silicon's indirect band structure alignment. This paper demonstrates phonon localization at the tip of silicon nanowires fabricated by galvanic displacement using wet electroless chemical etching of a bulk silicon wafer. High-resolution Raman micro-spectroscopy reveals that such arrayed structures of silicon nanowires display phonon localization behaviors, which could help their integration into the future generations of nano-engineered silicon nanowire-based devices such as photodetectors and solar cells.

20. Fabrication of large-area concave microlens array on silicon by femtosecond laser micromachining.

Deng, Zefang; Yang, Qing; Chen, Feng; Meng, Xiangwei; Bian, Hao; Yong, Jiale; Shan, Chao; Hou, Xun

2015-05-01

In this Letter, a novel fabrication of large-area concave microlens array (MLA) on silicon is demonstrated by combination of high-speed laser scanning, which would result in single femtosecond laser pulse ablation on surface of silicon, and subsequent wet etching. Microscale concave microlenses with tunable dimensions and accessional aspherical profile are readily obtained on the 1  cm × 1  cm silicon film, which are useful as optical elements for infrared (IR) applications. The aperture diameter and height of the microlens were characterized and the results reveal that they are both proportional to the laser scanning speed. Moreover, the optical property of high-performance silicon MLAs as a reflective homogenizer was investigated for the visible wavelength, and it can be easily extended to IR light. PMID:25927750

1. Vertically Integrated MEMS SOI Composite Porous Silicon-Crystalline Silicon Cantilever-Array Sensors: Concept for Continuous Sensing of Explosives and Warfare Agents

Stolyarova, Sara; Shemesh, Ariel; Aharon, Oren; Cohen, Omer; Gal, Lior; Eichen, Yoav; Nemirovsky, Yael

This study focuses on arrays of cantilevers made of crystalline silicon (c-Si), using SOI wafers as the starting material and using bulk micromachining. The arrays are subsequently transformed into composite porous silicon-crystalline silicon cantilevers, using a unique vapor phase process tailored for providing a thin surface layer of porous silicon on one side only. This results in asymmetric cantilever arrays, with one side providing nano-structured porous large surface, which can be further coated with polymers, thus providing additional sensing capabilities and enhanced sensing. The c-Si cantilevers are vertically integrated with a bottom silicon die with electrodes allowing electrostatic actuation. Flip Chip bonding is used for the vertical integration. The readout is provided by a sensitive Capacitance to Digital Converter. The fabrication, processing and characterization results are reported. The reported study is aimed towards achieving miniature cantilever chips with integrated readout for sensing explosives and chemical warfare agents in the field.

2. Joint Angle and Delay Estimation (JADE) in Antenna Array CDMA Systems

2002-01-01

The estimate of signals parameters is very important in wireless communications. In this paper, we combine subspace-based blind channel estimation algorithm with the extension of the JADE-WSF algorithm to jointly estimate the Angles-of-Arrival (AOAs) and delays of multipath signals arriving at an antenna array in Code Division Multiple Access (CDMA) systems. Our approach uses a collection of estimates of a consistent chip-sample of space-time vector channel. The channel estimates are assumed to have constant path AOA and delay over a finite number of symbols. Unlike the traditional MUltiple SIgnal Classification (MUSIC) and Estimation of Signal Parameters via Rotational Invariance Techniques (ESPRIT) algorithms for the estimation of signals parameters, the proposed method can work when the number of paths exceeds the number of antennas. The Cramer-Rao Bound (CRB) and simulations are provided.

3. A new angle for probing field-aligned irregularities with the Murchison Widefield Array

Loi, Shyeh Tjing; Cairns, Iver H; Trott, Cathryn M; Hurley-Walker, Natasha; Feng, Lu; Hancock, Paul J; Kaplan, David L

2016-01-01

Electron density irregularities in the ionosphere are known to be magnetically anisotropic, preferentially elongated along the lines of force. While many studies of their morphology have been undertaken by topside sounding and whistler measurements, it is only recently that detailed regional-scale reconstructions have become possible, enabled by the advent of widefield radio telescopes. Here we present a new approach for visualising and studying field-aligned irregularities (FAIs), which involves transforming interferometric measurements of TEC gradients onto a magnetic shell tangent plane. This removes the perspective distortion associated with the oblique viewing angle of the irregularities from the ground, facilitating the decomposition of dynamics along and across magnetic field lines. We apply this transformation to the dataset of Loi et al. [2015a], obtained on 15 October 2013 by the Murchison Widefield Array (MWA) radio telescope and displaying prominent FAIs. We study these FAIs in the new reference f...

4. Silicon material task. Part 3: Low-cost silicon solar array project

Roques, R. A.; Coldwell, D. M.

1977-01-01

The feasibility of a process for carbon reduction of low impurity silica in a plasma heat source was investigated to produce low-cost solar-grade silicon. Theoretical aspects of the reaction chemistry were studied with the aid of a computer program using iterative free energy minimization. These calculations indicate a threshold temperature exists at 2400 K below which no silicon is formed. The computer simulation technique of molecular dynamics was used to study the quenching of product species.

5. Mode hybridization and conversion in silicon-on-insulator nanowires with angled sidewalls.

Dai, Daoxin; Zhang, Ming

2015-12-14

The mode property and light propagation in a tapered silicon-on-insulator (SOI) nanowire with angled sidewalls is analyzed. Mode hybridization is observed and mode conversion between the TM fundamental mode and higher-order TE modes happens when light propagates in a waveguide taper which is used very often in the design of photonic integrated devices. This mode conversion ratio is possible to be very high (even close to 100%) when the taper is long enough to be adiabatic, which might be useful for some applications of multimode photonics. When the mode conversion is undesired to avoid any excess loss as well as crosstalk for photonic integrated circuits, one can depress the mode conversion by compensating the vertical asymmetry in the way of reducing the sidewall angle or introducing an optimal refractive index for the upper-cladding. It is also possible to eliminate the undesired mode conversion almost and improve the desired mode conversion greatly by introducing an abrupt junction connecting two sections with different widths to jump over the mode hybridization region. PMID:26699034

6. A Measurement of Lorentz Angle and Spatial Resolution of Radiation Hard Silicon Pixel Sensors

Gorelov, I; Hoeferkamp, M; Seidel, S C; Ciocio, A; Einsweiler, Kevin F; Gilchriese, M G D; Joshi, A; Kleinfelder, S A; Marchesini, R; Milgrome, O; Palaio, N; Pengg, F X; Richardson, J; Zizka, G; Ackers, M; Fischer, P; Keil, M; Meuser, S; Stockmanns, T; Treis, J; Wermes, N; Gössling, C; Hügging, F G; Wüstenfeld, J; Wunstorf, R; Barberis, D; Beccherle, R; Cervetto, M; Darbo, G; Gagliardi, G; Gemme, C; Morettini, P; Netchaeva, P; Osculati, B; Parodi, F; Rossi, L; Dao, K; Fasching, D; Blanquart, L; Breugnon, P; Calvet, D; Clemens, J C; Delpierre, P A; Hallewell, G D; Laugier, D; Mouthuy, T; Rozanov, A N; Trouilleau, C; Valin, I; Aleppo, M; Andreazza, A; Caccia, M; Lari, T; Meroni, C; Ragusa, F; Troncon, C; Vegni, G; Rohe, T; Boyd, G; Severini, H; Skubic, P L; Snow, J; Sícho, P; Tomasek, L; Vrba, V; Holder, M; Lipka, D; Ziolkowski, M; Cauz, D; D'Auria, S; del Papa, C; Grassman, H; Santi, L; Becks, K H; Gerlach, P; Grah, C; Gregor, I; Harenberg, T; Linder, C

2002-01-01

Silicon pixel sensors developed by the ATLAS collaboration to meet LHC requirements and to withstand hadronic irradiation to fluences of up to $10^{15} n_eq/cm^{2}$ have been evaluated using a test beam facility at CERN providing a magnetic field. The Lorentz angle was measured and found to alter from 9.0 deg. before irradiation, when the detectors operated at 150 V bias at B=1.48 T, to 3.1 deg after irradiation and operating at 600 V bias at 1.01 T. In addition to the effect due to magnetic field variation, this change is explained by the variation of the electric field inside the detectors arising from the different bias conditions. The depletion depths of irradiated sensors at various bias voltages were also measured. At 600 V bias 280 micron thick sensors depleted to ~200 micron after irradiation at the design fluence of 1 10^{15} 1 MeV n_eq/cm2 and were almost fully depleted at a fluence of 0.5 * 10^{15} 1 MeV n_eq/cm2. The spatial resolution was measured for angles of incidence between 0 deg and 30 deg....

7. Structure-thermal property correlation of aligned silicon dioxide nanorod arrays

Zhu, Jie; Zhu, Yu; Wu, Xuewang; Song, Helun; Zhang, Yaohui; Wang, Xiaojia

2016-06-01

Quantitative characterization of thermal properties of nanorod (NR) arrays appears to be challenging due to the complex combination of high volume of air voids, anisotropy, and structural non-uniformity. This work investigates the structure-thermal property correlation of arrays consisting of either vertically aligned or slanted silicon dioxide (SiO2) NRs, fabricated by the dynamic shadowing growth technique. We apply the frequency-dependent time-domain thermoreflectance method to quantify the thermal properties of SiO2 NR arrays that may possess inhomogeneity along the depth direction. The effective thermal conductivities of four SiO2 NR array films and one reference capping layer for the SiO2 NR array are obtained. The impact of the structure on the effective thermal conductivities of the SiO2 NR array is discussed. The lowest effective thermal conductivity among all samples in this work is found to be 0.13 W m-1 K-1 for the slanted NR array. We attribute the reduction in the effective thermal conductivity of the NR array to the discontinuous nature of SiO2 NRs, which reduces the density of the thermal transport channels and thus prevents heat flux from propagating downwards along the through-plane direction. The results from this work facilitate the potential applications of NR-array-based thermal insulators for micro-thermal devices.

8. Quantitative measurements of C-reactive protein using silicon nanowire arrays

Min-Ho Lee

2008-03-01

Full Text Available Min-Ho Lee, Kuk-Nyung Lee, Suk-Won Jung, Won-Hyo Kim, Kyu-Sik Shin, Woo-Kyeong SeongKorea Electronics Technology Institute, Gyeonggi, KoreaAbstract: A silicon nanowire-based sensor for biological application showed highly desirable electrical responses to either pH changes or receptor-ligand interactions such as protein disease markers, viruses, and DNA hybridization. Furthermore, because the silicon nanowire can display results in real-time, it may possess superior characteristics for biosensing than those demonstrated in previously studied methods. However, despite its promising potential and advantages, certain process-related limitations of the device, due to its size and material characteristics, need to be addressed. In this article, we suggest possible solutions. We fabricated silicon nanowire using a top-down and low cost micromachining method, and evaluate the sensing of molecules after transfer and surface modifications. Our newly designed method can be used to attach highly ordered nanowires to various substrates, to form a nanowire array device, which needs to follow a series of repetitive steps in conventional fabrication technology based on a vapor-liquid-solid (VLS method. For evaluation, we demonstrated that our newly fabricated silicon nanowire arrays could detect pH changes as well as streptavidin-biotin binding events. As well as the initial proof-of-principle studies, C-reactive protein binding was measured: electrical signals were changed in a linear fashion with the concentration (1 fM to 1 nM in PBS containing 1.37 mM of salts. Finally, to address the effects of Debye length, silicon nanowires coupled with antigen proteins underwent electrical signal changes as the salt concentration changed.Keywords: silicon nanowire array, C-reactive protein, vapor-liquid-solid method

9. Fabrication and electron field-emission of carbon nanofibers grown on silicon nanoporous pillar array

Highlights: ► Carbon nanofibers were grown on silicon nanoporous pillar array by a CVD method.► Low turn-on field, high density and stable FE current were obtained in CNTs/Si-NPA.► Defects in CNTs and Si array substrate contributes the excellent FE property. - Abstract: Random orientation carbon nanofibers (CNFs) were grown on silicon nanoporous pillar array (Si-NPA) by thermal chemical vapor deposition (CVD) method with acetylene (C2H2) as carbon precursor and Ni as the catalyst. The synthesized CNFs were mainly composed of amorphous carbon and disordered graphite layers with a core–shell like structure. And, the tangled CNFs and the regular silicon-pillar array formed a nanometer-micron hierarchy structure. The electron field-emission (FE) property of CNFs/Si-NPA was measured and low turn-on field, high-density and stable FE current, high enhancement factor were obtained. The outstanding FE performance of the CNFs/Si-NPA emitters was attributed to the random orientation and defects of CNFs, the undulate surface of the Si-NPA substrate.

10. Graded index and randomly oriented core-shell silicon nanowires with broadband and wide angle antireflection for photovoltaic cell applications

Pignalosa, P; Qiao, L; Tseng, M; Yi, Yasha

2011-01-01

Antireflection with broadband and wide angle properties is important for a wide range of applications on photovoltaic cells and display. The SiOx shell layer provides a natural antireflection from air to the Si core absorption layer. In this work, we have demonstrated the random core-shell silicon nanowires with both broadband (from 400nm to 900nm) and wide angle (from normal incidence to 60\\degree) antireflection characteristics within AM1.5 solar spectrum. The graded index structure from the randomly oriented core-shell (Air/SiOx/Si) nanowires may provide a potential avenue to realize a broadband and wide angle antireflection layer.

11. Phase 2 of the array automated assembly task for the low cost silicon solar array project

Petersen, R. C.

1980-01-01

Studies were conducted on several fundamental aspects of electroless nickel/solder metallization for silicon solar cells. A process, which precedes the electroless nickel plating with several steps of palladium plating and heat treatment, was compared directly with single step electroless nickel plating. Work was directed toward answering specific questions concerning the effect of silicon surface oxide on nickel plating, effects of thermal stresses on the metallization, sintering of nickel plated on silicon, and effects of exposure to the plating solution on solar cell characteristics. The process was found to be extremely lengthy and cumbersome, and was also found to produce a product virtually identical to that produced by single step electroless nickel plating, as shown by adhesion tests and electrical characteristics of cells under illumination.

12. Improved surface-enhanced Raman scattering of patterned gold nanoparticles deposited on silicon nanoporous pillar arrays

Jiang Weifen, E-mail: gingerwfj@yahoo.com.cn [Department of Mathematics and Information Science, North China Institute of Water Conservancy and Hydroelectric Power, Zhengzhou 450011 (China); Li Xingfu; Cai Hongtao [Department of Mathematics and Information Science, North China Institute of Water Conservancy and Hydroelectric Power, Zhengzhou 450011 (China); Li Xinjian [Department of Physics and Laboratory of Material Physics, Zhengzhou University, Zhengzhou 450052 (China)

2011-07-01

Large-area silicon nanoporous pillar arrays (Si-NPA) uniformly coated with gold nanoparticles was synthesized, and surface-enhanced Raman scattering of rhodamine 6G adsorbed on these gold nanoparticles were studied and compared. It's found that Au/Si-NPA substrate has a significantly high Raman signal sensitivity and good homogeneity. These are attributed to gold nanoparticles with narrow particle-size distribution uniformly coated on the surface and to the enlarged specific surface area for adsorption of target molecules brought by the porous silicon pillars.

13. Integrated optical dual-cantilever arrays in silica on silicon.

Cooper, Peter A; Carpenter, Lewis G; Mennea, Paolo L; Holmes, Christopher; Gates, James C; Smith, Peter G R

2014-12-29

A dual cantilever device has been demonstrated which can operate as a force sensor or variable attenuator. The device is fabricated using physical micromachining techniques that do not require cleanroom class facilities. The response of the device to mechanical actuation is measured, and shown to be well described by conventional fiber optic angular misalignment theory. The device has the potential to be utilized within integrated optical components for sensors or attenuators. An array of devices was fabricated with potential for parallel operation. PMID:25607148

14. Energy requirement for the production of silicon solar arrays

Lindmayer, J.; Wihl, M.; Scheinine, A.; Rosenfield, T.; Wrigley, C. Y.; Morrison, A.; Anderson, J.; Clifford, A.; Lafky, W.

1977-01-01

The results of a study to investigate the feasibility of manufacturing photovoltaic solar array modules by the use of energy obtained from similar or identical photovoltaic sources are presented. The primary objective of this investigation was the characterization of the energy requirements of current and developing technologies which comprise the photovoltaic field. For cross-checking the energies of prevailing technologies data were also used and the wide-range assessment of alternative technologies included different refinement methods, various ways of producing light sheets, semicrystalline cells, etc. Energy data are utilized to model the behavior of a future solar breeder plant under various operational conditions.

15. Beam Tilt-Angle Estimation for Monopole End-Fire Array Mounted on a Finite Ground Plane

Jia Cao

2015-01-01

Full Text Available A modified method for the beam tilt-angle estimation of monopole end-fire array mounted on finite ground plane is proposed. In the simplified model, the monopole array and ground plane are approximated to two line sources of transverse and longitudinal electric current, respectively. It is deduced that the beam tilt angle is a function about the length of ground plane in front of array Lg, the length of monopole array La, and the phase constant βα. After verifying the optimizing principle of monopole end-fire array, a 10-element monopole Yagi-Uda antenna satisfying Hansen-Woodyard condition is designed and measured for the analysis. By comparison and analysis, the value of βα is demonstrated to be the key point of the proposed method. And a slow wave monopole array is proved to be able to achieve a low beam tilt angle from end-fire with only a short-length ground plane.

16. Self-Assembled Wire Arrays and ITO Contacts for Silicon Nanowire Solar Cell Applications

YANG Cheng; ZHANG Gang; LEE Dae-Young; LI Hua-Min; LIM Young-Dae; Y00 Won Jong; PARK Young-Jun; KIM Jong-Min

2011-01-01

Self-assembly of silicon nanowire(SiNW)arrays is studied using SF6/02 plasma treatment. The self-assembly method can be applied to single- and poly-crystalline Si substrates. Plasma conditions can control the length and diameter of the SiNW arrays. Lower reflectance of the wire arrays over the wavelength range 200-1100nm is obtained. The conducting transparent indium-tin-oxide(ITO) electrode can be fully coated on the self-assembled SiNW arrays by sputtering. The ITO-coated SiNW solar cells show the same low surface light reflectance and a higher carrier collection efficiency than SiNW solar cells without ITO coating. An efficiency enhancement of around 3 times for ITO coated SiNW solar cells is demonstrated via experiments.

17. Synthesis, structure and photoelectrochemical properties of single crystalline silicon nanowire arrays

2010-01-31

In the present work, n-type silicon nanowire (n-SiNW) arrays have been synthesized by self-assembly electroless metal deposition (EMD) nanoelectrochemistry. The synthesized n-SiNW arrays have been submitted to scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and optical studies. Initial probes of the solar device conversion properties and the photovoltaic parameters such as short-circuit current, open-circuit potential, and fill factor of the n-SiNW arrays have been explored using a liquid-junction in a photoelectrochemical (PEC) system under white light. Moreover, a direct comparison between the PEC performance of a polished n-Si(100) and the synthesized n-SiNW array photoelectrodes has been done. The PEC performance was significantly enhanced on the n-SiNWs photoelectrodes compared with that on polished n-Si(100).

18. Self-Assembled Wire Arrays and ITO Contacts for Silicon Nanowire Solar Cell Applications

Self-assembly of silicon nanowire (SiNW) arrays is studied using SF6/O2 plasma treatment. The self-assembly method can be applied to single- and poly-crystalline Si substrates. Plasma conditions can control the length and diameter of the SiNW arrays. Lower reflectance of the wire arrays over the wavelength range 200–1100 nm is obtained. The conducting transparent indium-tin-oxide (ITO) electrode can be fully coated on the self-assembled SiNW arrays by sputtering. The ITO-coated SiNW solar cells show the same low surface light reflectance and a higher carrier collection efficiency than SiNW solar cells without ITO coating. An efficiency enhancement of around 3 times for ITO coated SiNW solar cells is demonstrated via experiments. (physics of gases, plasmas, and electric discharges)

19. Corporate array of micromachined dipoles on silicon wafer for 60 GHz communication systems

Sallam, M. O.

2013-03-01

In this paper, an antenna array operating at 60 GHz and realized on 0.675 mm thick silicon substrate is presented. The array is constructed using four micromachined half-wavelength dipoles fed by a corporate feeding network. Isolation between the antenna array and its feeding network is achieved via a ground plane. This arrangement leads to maximizing the broadside radiation with relatively high front-to-back ratio. Simulations have been carried out using both HFSS and CST, which showed very good agreement. Results reveal that the proposed antenna array has good radiation characteristics, where the directivity, gain, and radiation efficiency are around 10.5 dBi, 9.5 dBi, and 79%, respectively. © 2013 IEEE.

20. Off-chip beam steering with a one-dimensional optical phased array on silicon-on-insulator

Van Acoleyen, Karel; Bogaerts, Wim; Jágerská, Jana; Le Thomas, Nicolas; Houdré, Romuald; Baets, Roel

2009-01-01

Optical phased arrays are versatile components enabling rapid and precise beam steering. An integrated approach is followed in which a 1D optical phased array is fabricated on silicon-on-insulator. The optical phased array consists of 16 parallel grating couplers spaced 2 mu m apart. Steering in one direction is done thermo-optically by means of a titanium electrode on top of the structure using the phased array principle, while steering in the other direction is accomplished by wavelength tu...

1. A novel silicon array designed for intraoperative charged particle imaging

A novel Si-PIN imaging array is under investigation for a charged particle (beta, positron, or alpha) sensitive intraoperative camera to be used for (residual) tumor identification during surgery. This class of collimator-less nuclear imaging device has a higher signal response for direct interactions than its scintillator-optical detector-based counterparts. Monte Carlo simulations with 635 keV betas were performed, yielding maximum and projected ranges of 1.64 and 0.55 mm in Si. Up to 90% of these betas were completely absorbed in the first 0.30 mm. Based on these results, 300 μm thick prototype Si detector arrays were designed in a 16x16 crossed-grid arrangement with 0.8 mm wide orthogonal strips on 1.0 mm pitch. A NIM- and CAMAC-based high-density data acquisition and processing system was used to collect the list mode data. The system was calibrated by comparisons of measured spectra to energy deposition simulations or by direct measurement of various >100 keV conversion electron or beta emitters. Mean electronic noise per strip was 2 pixel size, and measurements of beta emitting point and line sources yielded FWHM resolutions of 1.5 (lateral) and 2.5 mm (diagonal), respectively, with the larger widths due to particle range blurring effects. Deconvolution of the finite source size yielded intrinsic resolutions that corresponded to the image pixel size. Transmission images of circle and line phantoms with various hole sizes and pitch were resolved with either pure beta or positron irradiation without a background correction. This novel semiconductor imaging device facilitates high charged particle and low gamma sensitivity, high signal/noise ratio, and allows for compact design to potentially aid surgical guidance by providing in situ images of clinical relevance

2. Develop silicone encapsulation systems for terrestrial silicon solar arrays. Final report

None

1979-12-01

This work resulted in two basic accomplishments. The first was the identification of DOW CORNING Q1-2577 as a suitable encapsulant material for use in cost effective encapsulation systems. The second was the preparation of a silicon-acrylic cover material containing a durable ultraviolet screening agent for the protection of photo-oxidatively sensitive polymers. The most expeditious method of fabrication is one in which the encapsulant material performs the combined function of adhesive, pottant, and outer cover. The costs of the encapsulant can be minimized by using it as a thin conformal coating. One encapsulation system using silicones was identified which provided protection to photovoltaic cells and survived the JPL qualification tests. This encapsulation system uses DOW CORNING Q1-2577, a conformal coating from Dow Corning, as the combined adhesive, pottant and cover material. The lowest cost encapsulation system using Q1-2577 had Super Dorlux as the substrate structural member. The overall material cost of this encapsulation system is 0.74 cents/ft/sup 2/ (1980 dollars) based on current material prices, which could decrease with increased production of Q1-2577. Subsequent to identifying the best silicone encapsulation system, a silicone acrylic cover material containing a durable ultraviolet screening agent was prepared and its effectiveness in protecting photo-oxidatively sensitive polymers was demonstrated.

3. Silicon crystallization in nanodot arrays organized by block copolymer lithography

Perego, Michele, E-mail: michele.perego@mdm.imm.cnr.it; Andreozzi, Andrea; Seguini, Gabriele [IMM-CNR, Laboratorio MDM (Italy); Schamm-Chardon, Sylvie; Castro, Celia; BenAssayag, Gerard [Université de Toulouse, nMat Group, CEMES-CNRS (France)

2014-12-15

Asymmetric polystyrene-b-polymethylmethacrylate (PS-b-PMMA) block copolymers are used to fabricate nanoporous PS templates with different pore diameter depending on the specific substrate neutralization protocol. The resulting polymeric templates are used as masks for the subsequent deposition of a thin (h = 5 nm) amorphous Si layer by electron beam evaporation. After removal of the polymeric film and of the silicon excess, well-defined hexagonally packed amorphous Si nanodots are formed on the substrate. Their average diameter (d < 20 nm), density (1.2 × 10{sup 11} cm{sup −2}), and lateral distribution closely mimic the original nanoporous template. Upon capping with SiO{sub 2} and high temperature annealing (1050 °C, N{sub 2}), each amorphous Si nanodot rearranges in agglomerates of Si nanocrystals (d < 4 nm). The average diameter and shape of these Si nanocrystals strongly depend on the size of the initial Si nanodot.

4. Silicon crystallization in nanodot arrays organized by block copolymer lithography

Asymmetric polystyrene-b-polymethylmethacrylate (PS-b-PMMA) block copolymers are used to fabricate nanoporous PS templates with different pore diameter depending on the specific substrate neutralization protocol. The resulting polymeric templates are used as masks for the subsequent deposition of a thin (h = 5 nm) amorphous Si layer by electron beam evaporation. After removal of the polymeric film and of the silicon excess, well-defined hexagonally packed amorphous Si nanodots are formed on the substrate. Their average diameter (d < 20 nm), density (1.2 × 1011 cm−2), and lateral distribution closely mimic the original nanoporous template. Upon capping with SiO2 and high temperature annealing (1050 °C, N2), each amorphous Si nanodot rearranges in agglomerates of Si nanocrystals (d < 4 nm). The average diameter and shape of these Si nanocrystals strongly depend on the size of the initial Si nanodot

5. Application of neural networks to digital pulse shape analysis for an array of silicon strip detectors

Flores, J. L.; Martel, I.; Jiménez, R.; Galán, J.; Salmerón, P.

2016-09-01

The new generation of nuclear physics detectors that used to study nuclear reactions is considering the use of digital pulse shape analysis techniques (DPSA) to obtain the (A,Z) values of the reaction products impinging in solid state detectors. This technique can be an important tool for selecting the relevant reaction channels at the HYDE (HYbrid DEtector ball array) silicon array foreseen for the Low Energy Branch of the FAIR facility (Darmstadt, Germany). In this work we study the feasibility of using artificial neural networks (ANNs) for particle identification with silicon detectors. Multilayer Perceptron networks were trained and tested with recent experimental data, showing excellent identification capabilities with signals of several isotopes ranging from 12C up to 84Kr, yielding higher discrimination rates than any other previously reported.

6. Large-area 2D periodic crystalline silicon nanodome arrays on nanoimprinted glass exhibiting photonic band structure effects

Two-dimensional silicon nanodome arrays are prepared on large areas up to 50 cm2 exhibiting photonic band structure effects in the near-infrared and visible wavelength region by downscaling a recently developed fabrication method based on nanoimprint-patterned glass, high-rate electron-beam evaporation of silicon, self-organized solid phase crystallization and wet-chemical etching. The silicon nanodomes, arranged in square lattice geometry with 300 nm lattice constant, are optically characterized by angular resolved reflection measurements, allowing the partial determination of the photonic band structure. This experimentally determined band structure agrees well with the outcome of three-dimensional optical finite-element simulations. A 16% photonic bandgap is predicted for an optimized geometry of the silicon nanodome arrays. By variation of the duration of the selective etching step, the geometry as well as the optical properties of the periodic silicon nanodome arrays can be controlled systematically. (paper)

7. A wearable multiplexed silicon nonvolatile memory array using nanocrystal charge confinement.

Kim, Jaemin; Son, Donghee; Lee, Mincheol; Song, Changyeong; Song, Jun-Kyul; Koo, Ja Hoon; Lee, Dong Jun; Shim, Hyung Joon; Kim, Ji Hoon; Lee, Minbaek; Hyeon, Taeghwan; Kim, Dae-Hyeong

2016-01-01

Strategies for efficient charge confinement in nanocrystal floating gates to realize high-performance memory devices have been investigated intensively. However, few studies have reported nanoscale experimental validations of charge confinement in closely packed uniform nanocrystals and related device performance characterization. Furthermore, the system-level integration of the resulting devices with wearable silicon electronics has not yet been realized. We introduce a wearable, fully multiplexed silicon nonvolatile memory array with nanocrystal floating gates. The nanocrystal monolayer is assembled over a large area using the Langmuir-Blodgett method. Efficient particle-level charge confinement is verified with the modified atomic force microscopy technique. Uniform nanocrystal charge traps evidently improve the memory window margin and retention performance. Furthermore, the multiplexing of memory devices in conjunction with the amplification of sensor signals based on ultrathin silicon nanomembrane circuits in stretchable layouts enables wearable healthcare applications such as long-term data storage of monitored heart rates. PMID:26763827

8. Monolithic electrically injected nanowire array edge-emitting laser on (001) silicon

Frost, Thomas

2014-08-13

A silicon-based laser, preferably electrically pumped, has long been a scientific and engineering goal. We demonstrate here, for the first time, an edge-emitting InGaN/GaN disk-in-nanowire array electrically pumped laser emitting in the green (λ = 533 nm) on (001) silicon substrate. The devices display excellent dc and dynamic characteristics with values of threshold current density, differential gain, T0 and small signal modulation bandwidth equal to 1.76 kA/cm2, 3 × 10-17 cm2, 232 K, and 5.8 GHz respectively under continuous wave operation. Preliminary reliability measurements indicate a lifetime of 7000 h. The emission wavelength can be tuned by varying the alloy composition in the quantum disks. The monolithic nanowire laser on (001)Si can therefore address wide-ranging applications such as solid state lighting, displays, plastic fiber communication, medical diagnostics, and silicon photonics. © 2014 American Chemical Society.

9. A pseudo 3D glass microprobe array: glass microprobe with embedded silicon for alignment and electrical interconnection during assembly

This study presents a process for the assembling of a pseudo 3D glass microprobe array. A glass microprobe with embedded silicon (ES) is batch fabricated by a glass reflow process. The silicon fixture and carrier for the assembly are also batch fabricated by silicon micromachining processes. First, the chips with a glass microprobe array are bonded by parylene-C to form the pseudo 3D glass microprobe array. The pseudo 3D microprobe array is then mounted on the silicon carrier. ES is employed for alignment during the assembly, and also acts as the electrical routing for signal recording. In application, the impedance of this glass microprobe is measured, and at 1 kHz it is 1.1 MΩ. Action potentials from rat brain cortex are also successfully recorded.

10. Generic technological platform for microfabricating silicon nitride micro- and nanopipette arrays

Guenat, Olivier T.; Generelli, Silvia; Dadras, Mohammad-Mehdi; Berdondini, L.; De Rooij, Nicolaas F; Koudelka-Hep, Milena

2007-01-01

In this paper, the design and the characterization of batch fabricated SixNy micropipette arrays with diameters ranging from 6 µm down to 250 nm are described. The process used to fabricate the micromachined pipettes includes a deep reactive ion etching step, followed by the deposition of two successive layers, a thermal oxide layer and a low stress, low pressure chemical vapor deposited silicon nitride layer, respectively. The diameter of the micropipettes could be modulated simply by choosi...

11. Microcrystalline silicon: Strain gauge and sensor arrays on flexible substrate for the measurement of high deformations

Kervran, Y.; De Sagazan, O.; Crand, S.; Coulon, N.; Mohammed-Brahim, T.; Brel, O

2015-01-01

This paper presents strain sensor arrays on flexible substrates able to measure local deformation induced by radii of curvature of few millimeters. Sensors use n-type doped microcrystalline silicon (μc-Si) as piezoresistive material, directly deposited on polyimide sheets at 165 °C. Sensitivity of individual sensors was investigated under tensile and compressive bending at various radii of curvature, down to 5 mm. A Transmission Line Method was used to extract the resistivity for each radius....

12. Development of silicon-germanium visible-near infrared arrays

Zeller, John W.; Rouse, Caitlin; Efstathiadis, Harry; Haldar, Pradeep; Lewis, Jay S.; Dhar, Nibir K.; Wijewarnasuriya, Priyalal; Puri, Yash R.; Sood, Ashok K.

2016-05-01

Photodetectors based on germanium which do not require cooling and can provide good near-infrared (NIR) detection performance offer a low-cost alternative to conventional infrared sensors based on material systems such as InGaAs, InSb, and HgCdTe. As a result of the significant difference in thermal expansion coefficients between germanium and silicon, tensile strain incorporated into Ge epitaxial layers deposited on Si utilizing specialized growth processes can extend the operational range of detection to 1600 nm and longer wavelengths. We have fabricated Ge based PIN photodetectors on 300 mm diameter Si wafers to take advantage of high throughput, large-area complementary metal-oxide semiconductor (CMOS) technology. This device fabrication process involves low temperature epitaxial deposition of Ge to form a thin p+ (boron) Ge seed/buffer layer, and subsequent higher temperature deposition of a thicker Ge intrinsic layer. This is followed by selective ion implantation of phosphorus of various concentrations to form n+ Ge regions, deposition of a passivating oxide cap, and then top copper contacts to complete the PIN detector devices. Various techniques including transmission electron microscopy (TEM) and secondary ion mass spectrometry (SIMS) have been employed to characterize the material and structural properties of the epitaxially grown layers and fabricated detector devices, and these results are presented. The I-V response of the photodetector devices with and without illumination was also measured, for which the Ge based photodetectors consistently exhibited low dark currents of around ~1 nA at -1 V bias.

13. Silicon microhole arrays architecture for stable and efficient photoelectrochemical cells using ionic liquids electrolytes

Shen, Xiaojuan; Chen, Ling; Li, Junnan; Zhao, Jie

2016-06-01

Silicon microhole arrays (SiMHs) structure is constructed and fabricated by a low-cost maskless anodic etching process, which is applied as the photoanode for the silicon photoelectrochemical (PEC) cells. The depths of silicon microhole arrays can be independently controlled by the etching time. The light-scattering properties are also investigated. Additionally, surface morphology analysis show that large hole diameters of SiMHs is very favourable for the full-filling of ionic liquids electrolyte. Therefore, better electrochemical contact as well as high ionic conductivity of the ionic liquids electrolyte renders the PEC SiMHs solar cells to exhibit more excellent performance. After optimization, the maximum PCE could be achieved at 4.04% for the SiMHs cell. The performance of the SiMHs cell is highly comparable to that of silicon nanowires cell. More importantly, the liquid-state electrolyte is confined in the unique microhole structure, which can obviously prevent the leakage of the ionic liquids electrolyte, resulting in much better long-term stability than the reference devices. These preliminary results validate the concept of interpenetrating networks with semiconductor structure/ILs junction to develop stable and efficient PEC cells.

14. Adjustable fragmentation in laser desorption/ionization from laser-induced silicon microcolumn arrays.

Chen, Yong; Vertes, Akos

2006-08-15

Laser-induced silicon microcolumn arrays (LISMA) were developed as matrix-free substrates for soft laser desorption/ionization mass spectrometry (SLDI-MS). When low-resistivity silicon wafers were irradiated in air, sulfur hexafluoride, or water environment with multiple pulses from a 3 x omega mode-locked Nd:YAG laser, columnar structures were formed on the surface. The radii of curvature of the column tips varied with the processing environment, ranging from approximately 120 nm in water, to nitrogen laser, the microcolumn arrays obtained in water environment readily produced molecular ions for peptides and synthetic polymers at low laser fluence. These surfaces demonstrated the best ion yield among the three arrays. The threshold laser fluence and ion yield were comparable to those observed in matrix-assisted laser desorption/ionization. Low-femtomole sensitivity and approximately 6000 Da mass range were achieved. At elevated laser fluence, efficient in-source decay was observed and extensive peptide sequence information was extracted from the resulting mass spectra. The versatility of LISMA was attributed to confinement effects due to the submicrometer morphology and to the surface, thermal, and optical properties of processed silicon. PMID:16906730

15. Nanoscale phosphorous atom arrays created using STM for the fabricaton of a silicon-based quantum computer

O'Brien, J. L.; Schofield, S. R.; Simmons, M. Y.; Clark, Robert G.; Dzurak, Andrew S.; Curson, N. J.; Kane, Bruce E.; McAlpine, N. S.; Hawley, Marilyn E.; Brown, Geoffrey W.

2001-11-01

Quantum computers offer the promise of formidable computational power for certain tasks. Of the various possible physical implementations of such a device, silicon based architectures are attractive for their scalability and ease of integration with existing silicon technology. These designs use either the electron or nuclear spin state of single donor atoms to store quantum information. Here we describe a strategy to fabricate an array of single phosphorus atoms in silicon for the construction of such a silicon based quantum computer. We demonstrate the controlled placement of single phosphorus bearing molecules on a silicon surface. This has been achieved by patterning a hydrogen mono-layer resist with a scanning tunneling microscope (STM) tip and exposing the patterned surface to phosphine (PH3) molecules. We also describe preliminary studies into a process to incorporate these surface phosphorus atoms into the silicon crystal at the array sites.

16. Fabrication of silicon nanotip arrays with high aspect ratio by cesium chloride self-assembly and dry etching

Xinshuai Zhang; Jing Liu; Bo Wang; Tianchong Zhang; Futing Yi

2014-01-01

Nanotip arrays with high aspect ratio, which have attracted much attention due to their potential applications, have been fabricated by many methods. Dry etching combined with self-assembly masks is widely used because of the convenience of dry etching and high throughput of self-assembly. In this paper, we report a method combining Cesium Chloride (CsCl) self-assembly with inductively coupled plasma (ICP) dry etching to fabricate silicon nanotip arrays with high aspect ratio and silicon nano...

17. Hypersonic phononic stopbands at small angles of wave incidence in porous silicon multilayers

Aliev, Gazi N.; Goller, Bernhard

2015-08-01

We report theoretical simulation and experimental observation of the mode conversion effect in a hypersonic distributed Bragg reflector of porous silicon. Acoustic transmission of longitudinal waves through the multilayered structure has been measured in the frequency range 0-3 GHz. It is found that the measured transmittance at the gap frequencies is always higher than that theoretically predicted for normal incidence. We attribute this to non-perpendicular wave propagation that was not deliberately sought, which subsequently increases the center gap transmittance due to the mode conversion effect. Oblique incidence with angles of about 1° results in truncated gap depth in acoustic transmission spectra from about  -80 dB, and deeper, to about  -40 dB and shallower. The spectra were simulated by employing the stiffness matrix method. Porosity-dependent acoustic viscous damping was included in the calculations. A way to optimize reflectors in the frequency range, where the forbidden gaps for longitudinal and shear waves overlap, is discussed.

18. Topological investigation of electronic silicon nanoparticulate aggregates using ultra-small-angle X-ray scattering

The network topology of two types of silicon nanoparticles, produced by high energy milling and pyrolysis of silane, in layers deposited from inks on permeable and impermeable substrates has been quantitatively characterized using ultra-small-angle X-ray scattering, supported by scanning electron microscopy observations. The milled particles with a highly polydisperse size distribution form agglomerates, which in turn cluster to form larger aggregates with a very high degree of aggregation. Smaller nanoparticles with less polydisperse size distribution synthesized by thermal catalytic pyrolysis of silane form small open clusters. The Sauter mean diameters of the primary particles of the two types of nanoparticles were obtained from USAXS particle volume to surface ratio, with values of ∼41 and ∼21 nm obtained for the high energy milled and pyrolysis samples, respectively. Assuming a log-normal distribution of the particles, the geometric standard deviation of the particles was calculated to be ∼1.48 for all the samples, using parameters derived from the unified fit to the USAXS data. The flow properties of the inks and substrate combination lead to quantitative changes in the mean particle separation, with slowly curing systems with good capillary flow resulting in denser networks with smaller aggregates and better contact between particles.

19. Fabrication of silicon nanowire arrays by macroscopic galvanic cell-driven metal catalyzed electroless etching in aerated HF solution.

Liu, Lin; Peng, Kui-Qing; Hu, Ya; Wu, Xiao-Ling; Lee, Shuit-Tong

2014-03-01

Macroscopic galvanic cell-driven metal catalyzed electroless etching (MCEE) of silicon in aqueous hydrofluoric acid (HF) solution is devised to fabricate silicon nanowire (SiNW) arrays with dissolved oxygen acting as the one and only oxidizing agent. The key aspect of this strategy is the use of a graphite or other noble metal electrode that is electrically coupled with silicon substrate. PMID:24323873

20. Millimeter-scale and large-angle self-collimation in a photonic crystal composed of silicon nanorods

Li, Hao; Li, Wei; Lin, Xulin; Qiu, Chao; Sheng, Zhen; Wang, Xi; Zou, Shichang; Gan, Fuwan

2013-01-01

We report the observation of a large-angle self-collimation phenomenon occurring in photonic crystals composed of nanorods. Electromagnetic waves incident onto such photonic crystals from directions covering a wide-range of incident angles become highly localized along a single array of rods, which results in narrow-beam propagation without divergence. A propagation length of 0.4 mm is experimentally observed over the wavelength range of 1540 nm to 1570 nm, even in the large incident angle case, which is a very considerable length scale for on-chip optical interconnection.

1. Bundle Block Adjustment of Airborne Three-Line Array Imagery Based on Rotation Angles

Yongjun Zhang

2014-05-01

Full Text Available In the midst of the rapid developments in electronic instruments and remote sensing technologies, airborne three-line array sensors and their applications are being widely promoted and plentiful research related to data processing and high precision geo-referencing technologies is under way. The exterior orientation parameters (EOPs, which are measured by the integrated positioning and orientation system (POS of airborne three-line sensors, however, have inevitable systematic errors, so the level of precision of direct geo-referencing is not sufficiently accurate for surveying and mapping applications. Consequently, a few ground control points are necessary to refine the exterior orientation parameters, and this paper will discuss bundle block adjustment models based on the systematic error compensation and the orientation image, considering the principle of an image sensor and the characteristics of the integrated POS. Unlike the models available in the literature, which mainly use a quaternion to represent the rotation matrix of exterior orientation, three rotation angles are directly used in order to effectively model and eliminate the systematic errors of the POS observations. Very good experimental results have been achieved with several real datasets that verify the correctness and effectiveness of the proposed adjustment models.

2. Bilayer–metal assisted chemical etching of silicon microwire arrays for photovoltaic applications

R. W. Wu

2016-02-01

Full Text Available Silicon microwires with lateral dimension from 5 μm to 20 μm and depth as long as 20 μm are prepared by bilayer metal assisted chemical etching (MaCE. A bilayer metal configuration (Metal 1 / Metal 2 was applied to assist etching of Si where metal 1 acts as direct catalyst and metal 2 provides mechanical support. Different metal types were investigated to figure out the influence of metal catalyst on morphology of etched silicon. We find that silicon microwires with vertical side wall are produced when we use Ag/Au bilayer, while cone–like and porous microwires formed when Pt/Au is applied. The different micro-/nano-structures in as-etched silicon are demonstrated to be due to the discrepancy of work function of metal catalyst relative to Si. Further, we constructed a silicon microwire arrays solar cells in a radial p–n junction configurations in a screen printed aluminum paste p–doping process.

3. Bilayer-metal assisted chemical etching of silicon microwire arrays for photovoltaic applications

Wu, R. W.; Yuan, G. D.; Wang, K. C.; Wei, T. B.; Liu, Z. Q.; Wang, G. H.; Wang, J. X.; Li, J. M.

2016-02-01

Silicon microwires with lateral dimension from 5 μm to 20 μm and depth as long as 20 μm are prepared by bilayer metal assisted chemical etching (MaCE). A bilayer metal configuration (Metal 1 / Metal 2) was applied to assist etching of Si where metal 1 acts as direct catalyst and metal 2 provides mechanical support. Different metal types were investigated to figure out the influence of metal catalyst on morphology of etched silicon. We find that silicon microwires with vertical side wall are produced when we use Ag/Au bilayer, while cone-like and porous microwires formed when Pt/Au is applied. The different micro-/nano-structures in as-etched silicon are demonstrated to be due to the discrepancy of work function of metal catalyst relative to Si. Further, we constructed a silicon microwire arrays solar cells in a radial p-n junction configurations in a screen printed aluminum paste p-doping process.

4. A large-area monolithic array of silicon drift detectors for medical imaging

Monolithic arrays of silicon drift detectors (SDDs) have been recently proposed to be used with scintillators for high-position-resolution γ-ray imaging applications. Thanks to the low electronics noise due to the small value of the output capacitance, the SDD offers better noise performances with respect to conventional photodiodes of the same geometry. Small monolithic arrays of SDDs have been used as photodetector of the scintillation light in a first prototype of Anger Camera for γ-ray imaging characterized by an intrinsic resolution better than 0.3 mm. In this work, we present a new large-area monolithic array of SDDs. It consists of a single chip composed of 77 single hexagonal units, each one with an active area of 8.7 mm2, for a total active area of the device of 6.7 cm2. It represents the largest monolithic array of SDDs with on-chip JFETs produced up to now for X-ray and γ-ray detection. The results achieved in the experimental characterization of a first prototype of the detector array are presented, both with X and visible photons. The energy resolution measured at 6 keV with the single unit of the array is of 142 eV at -10 oC, while a QE>90% was measured at λ=550 nm

5. Laser desorption/ionization from nanostructured surfaces: nanowires, nanoparticle films and silicon microcolumn arrays

Due to their optical properties and morphology, thin films formed of nanoparticles are potentially new platforms for soft laser desorption/ionization (SLDI) mass spectrometry. Thin films of gold nanoparticles (with 12±1 nm particle size) were prepared by evaporation-driven vertical colloidal deposition and used to analyze a series of directly deposited polypeptide samples. In this new SLDI method, the required laser fluence for ion detection was equal or less than what was needed for matrix-assisted laser desorption/ionization (MALDI) but the resulting spectra were free of matrix interferences. A silicon microcolumn array-based substrate (a.k.a. black silicon) was developed as a new matrix-free laser desorption ionization surface. When low-resistivity silicon wafers were processed with a 22 ps pulse length 3xω Nd:YAG laser in air, SF6 or water environment, regularly arranged conical spikes emerged. The radii of the spike tips varied with the processing environment, ranging from approximately 500 nm in water, to ∼2 μm in SF6 gas and to ∼5 μm in air. Peptide mass spectra directly induced by a nitrogen laser showed the formation of protonated ions of angiotensin I and II, substance P, bradykinin fragment 1-7, synthetic peptide, pro14-arg, and insulin from the processed silicon surfaces but not from the unprocessed areas. Threshold fluences for desorption/ionization were similar to those used in MALDI. Although compared to silicon nanowires the threshold laser pulse energy for ionization is significantly (∼10x) higher, the ease of production and robustness of microcolumn arrays offer complementary benefits

6. Laser desorption/ionization from nanostructured surfaces: nanowires, nanoparticle films and silicon microcolumn arrays

Chen Yong [Department of Chemistry, George Washington University, Washington, DC 20052 (United States); Luo Guanghong [Department of Chemistry, George Washington University, Washington, DC 20052 (United States); Diao Jiajie [Department of Physics, George Washington University, Washington, DC 20052 (United States); Chornoguz, Olesya [Department of Chemistry, George Washington University, Washington, DC 20052 (United States); Reeves, Mark [Department of Physics, George Washington University, Washington, DC 20052 (United States); Vertes, Akos [Department of Chemistry, George Washington University, Washington, DC 20052 (United States)

2007-04-15

Due to their optical properties and morphology, thin films formed of nanoparticles are potentially new platforms for soft laser desorption/ionization (SLDI) mass spectrometry. Thin films of gold nanoparticles (with 12{+-}1 nm particle size) were prepared by evaporation-driven vertical colloidal deposition and used to analyze a series of directly deposited polypeptide samples. In this new SLDI method, the required laser fluence for ion detection was equal or less than what was needed for matrix-assisted laser desorption/ionization (MALDI) but the resulting spectra were free of matrix interferences. A silicon microcolumn array-based substrate (a.k.a. black silicon) was developed as a new matrix-free laser desorption ionization surface. When low-resistivity silicon wafers were processed with a 22 ps pulse length 3x{omega} Nd:YAG laser in air, SF{sub 6} or water environment, regularly arranged conical spikes emerged. The radii of the spike tips varied with the processing environment, ranging from approximately 500 nm in water, to {approx}2 {mu}m in SF{sub 6} gas and to {approx}5 {mu}m in air. Peptide mass spectra directly induced by a nitrogen laser showed the formation of protonated ions of angiotensin I and II, substance P, bradykinin fragment 1-7, synthetic peptide, pro14-arg, and insulin from the processed silicon surfaces but not from the unprocessed areas. Threshold fluences for desorption/ionization were similar to those used in MALDI. Although compared to silicon nanowires the threshold laser pulse energy for ionization is significantly ({approx}10x) higher, the ease of production and robustness of microcolumn arrays offer complementary benefits.

7. High-performance uncooled amorphous silicon video graphics array and extended graphics array infrared focal plane arrays with 17-μm pixel pitch

Tissot, Jean-Luc; Tinnes, Sébastien; Durand, Alain; Minassian, Christophe; Robert, Patrick; Vilain, Michel; Yon, Jean-Jacques

2011-06-01

The high level of accumulated expertise by ULIS and CEA/LETI on uncooled microbolometers made from amorphous silicon with 45, 35, and 25 μm enables ULIS to develop video graphics array (VGA) and extended graphics array (XGA) infrared focal plane array (IRFPA) formats with 17-μm pixel pitch to fulfill every application. These detectors keep all the recent innovations developed on the 25-μm pixel-pitch read out integrated circuit (ROIC) (detector configuration by serial link, low power consumption, and wide electrical dynamic range). The specific appeal of these units lies in the high spatial resolution it provides while keeping the small thermal time constant. The reduction of the pixel pitch turns the VGA array into a product well adapted for high-resolution and compact systems and the XGA a product well adapted for high-resolution imaging systems. High electro-optical performances have been demonstrated with noise equivalent temperature difference (NETD) ROIC design. This technology node paves the way to high-end products as well as low-end, compact, smaller formats, such as 320 × 240 and 160 × 120 or smaller.

8. Broadband High Efficiency Fractal-Like and Diverse Geometry Silicon Nanowire Arrays for Photovoltaic Applications

AL-Zoubi, Omar H.

Solar energy has many advantages over conventional sources of energy. It is abundant, clean and sustainable. One way to convert solar energy directly into electrical energy is by using the photovoltaic solar cells (PVSC). Despite PVSC are becoming economically competitive, they still have high cost and low light to electricity conversion efficiency. Therefore, increasing the efficiency and reducing the cost are key elements for producing economically more competitive PVSC that would have significant impact on energy market and saving environment. A significant percentage of the PVSC cost is due to the materials cost. For that, thin films PVSC have been proposed which offer the benefits of the low amount of material and fabrication costs. Regrettably, thin film PVSC show poor light to electricity conversion efficiency because of many factors especially the high optical losses. To enhance conversion efficiency, numerous techniques have been proposed to reduce the optical losses and to enhance the absorption of light in thin film PVSC. One promising technique is the nanowire (NW) arrays in general and the silicon nanowire (SiNW) arrays in particular. The purpose of this research is to introduce vertically aligned SiNW arrays with enhanced and broadband absorption covering the entire solar spectrum while simultaneously reducing the amount of material used. To this end, we apply new concept for designing SiNW arrays based on employing diversity of physical dimensions, especially radial diversity within certain lattice configurations. In order to study the interaction of light with SiNW arrays and compute their optical properties, electromagnetic numerical modeling is used. A commercial numerical electromagnetic solver software package, high frequency structure simulation (HFSS), is utilized to model the SiNW arrays and to study their optical properties. We studied different geometries factors that affect the optical properties of SiNW arrays. Based on this study, we

9. Research on analytical model and design formulas of permanent magnetic bearings based on Halbach array with arbitrary segmented magnetized angle

Wang, Nianxian; Wang, Dongxiong; Chen, Kuisheng; Wu, Huachun

2016-07-01

The bearing capacity of permanent magnetic bearings can be improved efficiently by using the Halbach array magnetization. However, the research on analytical model of Halbach array PMBs with arbitrary segmented magnetized angle has not been developed. The application of Halbach array PMBs has been limited by the absence of the analytical model and design formulas. In this research, the Halbach array PMBs with arbitrary segmented magnetized angle has been studied. The magnetization model of bearings is established. The magnetic field distribution model of the permanent magnet array is established by using the scalar magnetic potential model. On the basis of this, the bearing force model and the bearing stiffness model of the PMBs are established based on the virtual displacement method. The influence of the pair of magnetic rings in one cycle and the structure parameters of PMBs on the maximal bearing capacity and support stiffness characteristics are studied. The reference factors for the design process of PMBs have been given. Finally, the theoretical model and the conclusions are verified by the finite element analysis.

10. Fabrication of silicon nanotip arrays with high aspect ratio by cesium chloride self-assembly and dry etching

Xinshuai Zhang

2014-03-01

Full Text Available Nanotip arrays with high aspect ratio, which have attracted much attention due to their potential applications, have been fabricated by many methods. Dry etching combined with self-assembly masks is widely used because of the convenience of dry etching and high throughput of self-assembly. In this paper, we report a method combining Cesium Chloride (CsCl self-assembly with inductively coupled plasma (ICP dry etching to fabricate silicon nanotip arrays with high aspect ratio and silicon nanotip arrays with aspect ratio 15 have been achieved after optimization of all parameters.

11. A two dimensional silicon detectors array for quality assurance in stereotactic radiotherapy: MagicPlate-512

Aldosari, A. H.; Petasecca, M., E-mail: marcop@uow.edu.au; Espinoza, A.; Newall, M.; Fuduli, I.; Porumb, C.; Alshaikh, S.; Alrowaili, Z. A.; Weaver, M.; Metcalfe, P.; Lerch, M. L. F.; Rosenfeld, A. B. [Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW 2500 (Australia); Carolan, M. [Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW 2500, Australia and Illawarra Cancer Care Centre, Wollongong Hospital, Wollongong, NSW 2500 (Australia); Perevertaylo, V. [SPA-BIT, KIEV 02232 (Ukraine)

2014-09-15

Purpose: Silicon diode arrays are commonly implemented in radiation therapy quality assurance applications as they have a number of advantages including: real time operation (compared to the film) and high spatial resolution, large dynamic range and small size (compared to ionizing chambers). Most diode arrays have detector pitch that is too coarse for routine use in small field applications. The goal of this work is to characterize the two-dimensional monolithic silicon diode array named “MagicPlate-512” (MP512) designed for QA in stereotactic body radiation therapy (SBRT) and stereotactic radio surgery (SRS). Methods: MP512 is a silicon monolithic detector manufactured on ap-type substrate. An array contains of 512 pixels with size 0.5 × 0.5 mm{sup 2} and pitch 2 mm with an overall dimension of 52 × 52 mm{sup 2}. The MP512 monolithic detector is wire bonded on a printed circuit board 0.5 mm thick and covered by a thin layer of raisin to preserve the silicon detector from moisture and chemical contamination and to protect the bonding wires. Characterization of the silicon monolithic diode array response was performed, and included pixels response uniformity, dose linearity, percent depth dose, output factor, and beam profiling for beam sizes relevant to SBRT and SRS and depth dose response in comparison with ionization chamber. Results: MP512 shows a good dose linearity (R{sup 2} = 0.998) and repeatability within 0.2%. The measured depth dose response for field size of 10 × 10 cm{sup 2} agreed to within 1.3%, when compared to a CC13 ionization chamber for depths in PMMA up to 30 cm. The output factor of a 6 MV Varian 2100EX medical linac beam measured by MP512 at the isocenter agrees to within 2% when compared to PTW diamond, Scanditronix point EDD-2 diode and MOSkin detectors for field sizes down to 1 × 1 cm{sup 2}. An over response of 4% was observed for square beam size smaller than 1 cm when compared to EBT3 films, while the beam profiles (FWHM) of MP

12. A two dimensional silicon detectors array for quality assurance in stereotactic radiotherapy: MagicPlate-512

Purpose: Silicon diode arrays are commonly implemented in radiation therapy quality assurance applications as they have a number of advantages including: real time operation (compared to the film) and high spatial resolution, large dynamic range and small size (compared to ionizing chambers). Most diode arrays have detector pitch that is too coarse for routine use in small field applications. The goal of this work is to characterize the two-dimensional monolithic silicon diode array named “MagicPlate-512” (MP512) designed for QA in stereotactic body radiation therapy (SBRT) and stereotactic radio surgery (SRS). Methods: MP512 is a silicon monolithic detector manufactured on ap-type substrate. An array contains of 512 pixels with size 0.5 × 0.5 mm2 and pitch 2 mm with an overall dimension of 52 × 52 mm2. The MP512 monolithic detector is wire bonded on a printed circuit board 0.5 mm thick and covered by a thin layer of raisin to preserve the silicon detector from moisture and chemical contamination and to protect the bonding wires. Characterization of the silicon monolithic diode array response was performed, and included pixels response uniformity, dose linearity, percent depth dose, output factor, and beam profiling for beam sizes relevant to SBRT and SRS and depth dose response in comparison with ionization chamber. Results: MP512 shows a good dose linearity (R2 = 0.998) and repeatability within 0.2%. The measured depth dose response for field size of 10 × 10 cm2 agreed to within 1.3%, when compared to a CC13 ionization chamber for depths in PMMA up to 30 cm. The output factor of a 6 MV Varian 2100EX medical linac beam measured by MP512 at the isocenter agrees to within 2% when compared to PTW diamond, Scanditronix point EDD-2 diode and MOSkin detectors for field sizes down to 1 × 1 cm2. An over response of 4% was observed for square beam size smaller than 1 cm when compared to EBT3 films, while the beam profiles (FWHM) of MP512 match to within 2% the data

13. Design and development of compact readout electronics with silicon photomultiplier array for a compact imaging detector

This work aims at developing compact readout electronics for a compact imaging detector module with silicon photomultiplier (SPM) array. The detector module consists of a LYSO crystal array coupling with a SensL's 4 × 4 SPM array. A compact multiplexed readout based on a discretized positioning circuit (DPC) was developed to reduce the readout channels from 16 to 4 outputs. Different LYSO crystal arrays of 4 × 4, 8 × 8 and 12 × 12 with pixel sizes of 3.2, 1.6 and 1.0 mm respectively, have been tested with the compact readout board using a 137Cs source. The initial results show that the compact imaging detector module with the compact multiplexed readout could clearly resolve 1 mm × 1 mm × 10 mm LYSO scintillation crystal array except those at the edges. The detector's intrinsic spatial resolution up to 1 mm can be achieved with the 3 mm × 3 mm size SPMArray4 through light sharing and compact multiplexed readout. Our results indicate that this detector module is feasible for the development of high-resolution compact PET. (authors)

14. Conjugated polymer–silicon nanowire array hybrid Schottky diode for solar cell application

The hybrid Schottky diode based on silicon nanowire arrays (SiNWs) and poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT:PSS) has been fabricated for high performance solar cells. The length of SiNWs on a silicon substrate, which is prepared by metal-assisted chemical etching, can be tuned by adjusting the length of the etching time. In addition, the average distances between the adjacent silicon nanowires can be controlled by changing the immersing time in a saturated PCl5 solution. The hybrid devices are made from the SiNWs with different wire lengths and various distances between adjacent wires by spin-casting PEDOT:PSS on the silicon substrates. It is found that the length and density play leading roles in the electric output characteristics. The device made from SiNWs with optimum morphology can achieve a power conversion efficiency of 7.3%, which is much improved in comparison with that of the planar one. The measurement of the transient photovoltage decay and the analysis of the current versus voltage curve indicate that the charge recombination process is a dominant factor on the device performance. (paper)

15. Broadband absorptance enhancement of silicon nanowire arrays with germanium as the substrate

Wang, Han; Xia, Xin-Lin

2013-08-01

A composite structure with silicon nanowire arrays on germanium substrate is proposed as a good candidate for highly efficient solar cells. The Bruggeman approximation considering anisotropic wave propagating in uniaxial media is employed to calculate the radiative properties. Meantime, finite-difference time-domain (FDTD) method is used to verify for both normal and oblique incidence. It is found that the composite structure has superior absorption characteristics over thin Si film, particularly near the bandgap. With a thickness only of 4 μm, the composite structure improved the absorptance to above 0.6 across the whole wavelength band with the lattice constant of 100 nm, and the ultimate efficiency about 10% is higher than that of infinite bulk silicon, owing to the combined effects of suppressed reflection and high light trapping capability. To better understand the absorption enhancement process in the composite structure, the photogeneration profiles are provided by using FDTD method.

16. Integration of field emitter array and thin-film transistor using polycrystalline silicon process technology

We present the monolithic integration of a gated polycrystalline silicon field emitter array (poly-Si FEA) and a thin-film transistor(TFT) on an insulating substrate for active-matrix field emission displays (AMFEDs). The TFT was designed to have low off-state currents even at a high drain voltage. Amorphous silicon has been used as a starting material of the poly-Si FEA for improving surface smoothness and uniformity of the tips, and the gate holes have been formed by using an etch-back process. The integrated poly-Si TFT controlled electron emissions of the poly-Si FEA actively, resulting in great improvement in the emission reliability along with a low-voltage control, below 15 V, of field emission, The developed technology has potential applications in AMFEDs on glass substrates

17. Integration of field emitter array and thin-film transistor using polycrystalline silicon process technology

Song, Y H; Kang, S Y; Park Jeong Man; Cho, K I

1998-01-01

We present the monolithic integration of a gated polycrystalline silicon field emitter array (poly-Si FEA) and a thin-film transistor(TFT) on an insulating substrate for active-matrix field emission displays (AMFEDs). The TFT was designed to have low off-state currents even at a high drain voltage. Amorphous silicon has been used as a starting material of the poly-Si FEA for improving surface smoothness and uniformity of the tips, and the gate holes have been formed by using an etch-back process. The integrated poly-Si TFT controlled electron emissions of the poly-Si FEA actively, resulting in great improvement in the emission reliability along with a low-voltage control, below 15 V, of field emission, The developed technology has potential applications in AMFEDs on glass substrates.

18. Comparison of ordered and disordered silicon nanowire arrays: experimental evidence of photonic crystal modes.

Dhindsa, Navneet; Saini, Simarjeet S

2016-05-01

We experimentally compared the reflectance between ordered and disordered silicon nanowires to observe the evidence of photonic crystal modes. For similar diameters, the resonance peaks for the ordered nanowires at a spacing of 400 nm was at a shorter wavelength than the disordered nanowires, consistent to the excitation of photonic crystal modes. Furthermore, the resonant wavelength didn't shift while changing the density of the disordered nanowires, whereas there was a significant shift observed in the ordered ones. At an ordered spacing of 800 nm, the resonance wavelength approached that of the disordered structures, indicating that the ordered structures were starting to behave like individual waveguides. To our knowledge, this is the first direct experimental observation of photonic crystal modes in vertical periodic silicon nanowire arrays. PMID:27128070

19. Development of a silicon strip detector array for nuclear structure physics

The Edinburgh nuclear physics group has been exploiting some of the unique features of silicon strip detectors (SSDs) in a variety of nuclear structure experiments using high energy photons and heavy-ion projectiles. Current experimental applications make use of large area (≅ 4-25 cm2), totally depleted SSDs with depletion thicknesses in the range ≅ 150-1000 μm and strip pitches of 2000 μm. In addition, two new device configurations are currently undergoing evaluation tests for future applications. These configurations are: (i) double-sided silicon strip detectors (i.e. ''quasi-pixel'' devices), and (ii) position sensitive silicon strip detectors. Silicon strip detectors are potentially a powerful tool for nuclear structure physics applications where charged particle detection is required. It is possible to construct charged particle detection systems with good energy and position resolution, large solid angle and high data throughput. To date however, it has not been possible to fully exploit the potential of SSDs because of the high cost and limited availability of appropriate instrumentation. To overcome this problem we are developing low cost hybrid microelectronic instrumentation in collaboration with the SERC Rutherford-Appleton Laboratory. (orig.)

20. Electronic transport mechanisms in scaled gate-all-around silicon nanowire transistor arrays

Low-frequency noise is used to study the electronic transport in arrays of 14 nm gate length vertical silicon nanowire devices. We demonstrate that, even at such scaling, the electrostatic control of the gate-all-around is sufficient in the sub-threshold voltage region to confine charges in the heart of the wire, and the extremely low noise level is comparable to that of high quality epitaxial layers. Although contact noise can already be a source of poor transistor operation above threshold voltage for few nanowires, nanowire parallelization drastically reduces its impact

1. Micro-contacting of single and periodically arrayed columnar silicon structures by focused ion beam techniques

Friedrich, F., E-mail: felice.friedrich@tu-berlin.de; Herfurth, N.; Teodoreanu, A.-M.; Boit, C. [TU Berlin, FG HLB/PVcomB, Sekr. E4, Einsteinufer 19, D-10587 Berlin (Germany); Sontheimer, T.; Preidel, V.; Rech, B. [Helmholtz-Zentrum Berlin für Materialien und Energie, E-IS, Kekuléstr. 5, D-12489 Berlin (Germany)

2014-06-16

Micron-sized, periodic crystalline Silicon columns on glass substrate were electrically contacted with a transparent conductive oxide front contact and a focused ion beam processed local back contact. Individual column contacts as well as arrays of >100 contacted columns were processed. Current-voltage characteristics of the devices were determined. By comparison with characteristics obtained from adapted device simulation, the absorber defect density was reconstructed. The contacting scheme allows the fabrication of testing devices in order to evaluate the electronic potential of promising semiconductor microstructures.

2. Characterization of a highly-segmented silicon prototype for the TRACE array

Gelain M.

2014-03-01

Full Text Available In view of the construction of novel and high-sensitive instrumentation for the emerging ISOL facilities new prototypes have being implemented and tested. The contribution focuses at the investigation of the detection efficiency of an innovative silicon-pad prototype, which is the key element for the construction of the TRACE array, pursued for the SPES facility based at the Legnaro National Laboratories (Italy. The inter-pad size has been estimated by using a commercial 100-MHz-14-bit CAEN digitizer for sampling the signals obtained by an alpha-source scan over the inter-pad region.

3. Micro-contacting of single and periodically arrayed columnar silicon structures by focused ion beam techniques

Micron-sized, periodic crystalline Silicon columns on glass substrate were electrically contacted with a transparent conductive oxide front contact and a focused ion beam processed local back contact. Individual column contacts as well as arrays of >100 contacted columns were processed. Current-voltage characteristics of the devices were determined. By comparison with characteristics obtained from adapted device simulation, the absorber defect density was reconstructed. The contacting scheme allows the fabrication of testing devices in order to evaluate the electronic potential of promising semiconductor microstructures.

4. Enhanced Field Emission from Well-Patterned Silicon Nanoporous Pillar Arrays

FU Xiao-Nan; LI Xin-Jian

2006-01-01

@@ The silicon nanoporous pillar array (Si-NPA) is synthesized by using hydrothermal etching method, and the electron field emission properties are studied. The results show that Si-NPA has a low turn-on field of 1.48 V/μm at the emission current of 0.1 μA and its field emission is relatively stable. The field emission enhancement of Si-NPA is believed to originate from its unique morphology and structure. Our finding demonstrates that the Si-NPA is a promising candidate material for field emission applications.

5. Development of a multichannel integrated circuit for Silicon Photo-Multiplier arrays readout

Comerma Montells, Albert

2014-01-01

[eng] The aim of this thesis is to present a solution for the readout of Silicon Photo-Multipliers (SiPMs) arrays improving currently implemented systems. Using as a starting point previous designs with similar objectives a novel current mode input stage has been designed and tested. To start with the design a valid model has been used to generate realistic output from the SiPMs depending on light input. Design has been performed in first place focusing in general applications for medical ...

6. Biocompatibility of silicon-based arrays of electrodes coupled to organotypic hippocampal brain slice cultures

Kristensen, Bjarne Winther; Noraberg, J; Thiébaud, P;

2001-01-01

In this study we examined the passive biocompatibility of a three-dimensional microelectrode array (MEA), designed to be coupled to organotypic brain slice cultures for multisite recording of electrophysiological signals. Hippocampal (and corticostriatal) brain slices from 1-week-old (and newborn......-methyl-D-aspartate (NMDA) and the neurotoxin trimethyltin (TMT), as demonstrated by the cellular uptake of propidium iodide (PI), which was used as a reproducible and quantifiable marker for neuronal degeneration. We conclude that organotypic brain slice cultures can grow on silicon-based three-dimensional microelectrode...

7. The fabrication of highly ordered block copolymer micellar arrays: control of the separation distances of silicon oxide dots.

Yoo, Hana; Park, Soojin

2010-06-18

We demonstrate the fabrication of highly ordered silicon oxide dotted arrays prepared from polydimethylsiloxane (PDMS) filled nanoporous block copolymer (BCP) films and the preparation of nanoporous, flexible Teflon or polyimide films. Polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) films were annealed in toluene vapor to enhance the lateral order of micellar arrays and were subsequently immersed in alcohol to produce nano-sized pores, which can be used as templates for filling a thin layer of PDMS. When a thin layer of PDMS was spin-coated onto nanoporous BCP films and thermally annealed at a certain temperature, the PDMS was drawn into the pores by capillary action. PDMS filled BCP templates were exposed to oxygen plasma environments in order to fabricate silicon oxide dotted arrays. By addition of PS homopolymer to PS-b-P2VP copolymer, the separation distances of micellar arrays were tuned. As-prepared silicon oxide dotted arrays were used as a hard master for fabricating nanoporous Teflon or polyimide films by spin-coating polymer precursor solutions onto silicon patterns and peeling off. This simple process enables us to fabricate highly ordered nanoporous BCP templates, silicon oxide dots, and flexible nanoporous polymer patterns with feature size of sub-20 nm over 5 cm x 5 cm. PMID:20498523

8. Fabrication of silicon nanowire arrays by near-field laser ablation and metal-assisted chemical etching

Brodoceanu, D.; Alhmoud, H. Z.; Elnathan, R.; Delalat, B.; Voelcker, N. H.; Kraus, T.

2016-02-01

We present an elegant route for the fabrication of ordered arrays of vertically-aligned silicon nanowires with tunable geometry at controlled locations on a silicon wafer. A monolayer of transparent microspheres convectively assembled onto a gold-coated silicon wafer acts as a microlens array. Irradiation with a single nanosecond laser pulse removes the gold beneath each focusing microsphere, leaving behind a hexagonal pattern of holes in the gold layer. Owing to the near-field effects, the diameter of the holes can be at least five times smaller than the laser wavelength. The patterned gold layer is used as catalyst in a metal-assisted chemical etching to produce an array of vertically-aligned silicon nanowires. This approach combines the advantages of direct laser writing with the benefits of parallel laser processing, yielding nanowire arrays with controlled geometry at predefined locations on the silicon surface. The fabricated VA-SiNW arrays can effectively transfect human cells with a plasmid encoding for green fluorescent protein.

9. Plasmon enhanced broadband optical absorption in ultrathin silicon nanobowl array for photoactive devices applications

Sun, Rui-Nan; Peng, Kui-Qing, E-mail: kq-peng@bnu.edu.cn; Hu, Bo; Hu, Ya; Zhang, Fu-Qiang [Department of Physics and Beijing Key Laboratory of Energy Conversion and Storage Materials, Beijing Normal University, Beijing 100875 (China); Lee, Shuit-Tong [Institute of Functional Nano and Soft Materials (FUNSOM) and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215123 (China)

2015-07-06

Both photonic and plasmonic nanostructures are key optical components of photoactive devices for light harvesting, enabling solar cells with significant thickness reduction, and light detectors capable of detecting photons with sub-band gap energies. In this work, we study the plasmon enhanced broadband light absorption and electrical properties of silicon nanobowl (SiNB) arrays. The SiNB-metal photonic-plasmonic nanostructure-based devices exhibited superior light-harvesting ability across a wide range of wavelengths up to the infrared regime well below the band edge of Si due to effective optical coupling between the SiNB array and incident sunlight, as well as electric field intensity enhancement around metal nanoparticles due to localized surface plasmon resonance. The photonic-plasmonic nanostructure is expected to result in infrared-light detectors and high-efficiency solar cells by extending light-harvesting to infrared frequencies.

10. Surface-assisted laser desorption/ionization mass spectrometry using ordered silicon nanopillar arrays.

Alhmoud, Hashim Z; Guinan, Taryn M; Elnathan, Roey; Kobus, Hilton; Voelcker, Nicolas H

2014-11-21

Surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) is ideally suited for the high-throughput analysis of small molecules in bodily fluids (e.g. saliva, urine, and blood plasma). A key application for this technique is the testing of drug consumption in the context of workplace, roadside, athlete sports and anti-addictive drug compliance. Here, we show that vertically-aligned ordered silicon nanopillar (SiNP) arrays fabricated using nanosphere lithography followed by metal-assisted chemical etching (MACE) are suitable substrates for the SALDI-MS detection of methadone and small peptides. Porosity, length and diameter are fabrication parameters that we have explored here in order to optimize analytical performance. We demonstrate the quantitative analysis of methadone in MilliQ water down to 32 ng mL(-1). Finally, the capability of SiNP arrays to facilitate the detection of methadone in clinical samples is also demonstrated. PMID:25268849

11. Photosensor Characterization for the Cherenkov Telescope Array: Silicon Photomultiplier versus Multi-Anode Photomultiplier Tube

Bouvier, Aurelien; Johnson, Caitlin; Kuznetsov, Andrey; Williams, David; Otte, Nepomuk; Strausbaugh, Robert; Hidaka, Naoya; Tajima, Hiroyasu; Hinton, Jim; White, Richard; Errando, Manel; Mukherjee, Reshmi

2013-01-01

Photomultiplier tube technology has been the photodetector of choice for the technique of imaging atmospheric Cherenkov telescopes since its birth more than 50 years ago. Recently, new types of photosensors are being contemplated for the next generation Cherenkov Telescope Array. It is envisioned that the array will be partly composed of telescopes using a Schwarzschild-Couder two mirror design never built before which has significantly improved optics. The camera of this novel optical design has a small plate scale which enables the use of compact photosensors. We present an extensive and detailed study of the two most promising devices being considered for this telescope design: the silicon photomultiplier and the multi-anode photomultiplier tube. We evaluated their most critical performance characteristics for imaging gamma-ray showers, and we present our results in a cohesive manner to clearly evaluate the advantages and disadvantages that both types of device have to offer in the context of GeV-TeV gamma...

12. Fabrication of High Aspect Ratio Micro-Penning-Malmberg Gold Plated Silicon Trap Arrays

Narimannezhad, Alireza; Weber, Marc H; Lynn, Kelvin G

2013-01-01

Acquiring a portable high density charged particles trap might consist of an array of micro-Penning-Malmberg traps (microtraps) with substantially lower end barriers potential than conventional Penning-Malmberg traps [1]. We report on the progress of the fabrication of these microtraps designed for antimatter storage such as positrons. The fabrication of large length to radius aspect ratio (1000:1) microtrap arrays involved advanced techniques including photolithography, deep reactive ion etching (DRIE) of silicon wafers to achieve through-vias, gold sputtering of the wafers on the surfaces and inside the vias, and thermal compression bonding of the wafers. This paper describes the encountered issues during fabrication and addresses geometry errors and asymmetries. In order to minimize the patch effects on the lifetime of the trapped positrons, the bonded stacks were gold electroplated to achieve a uniform gold surface. We show by simulation and analytical calculation that how positrons confinement time depen...

13. Influences of temperature and etching voltage on the surface morphology of photo-electro-chemical etching for silicon microchannel arrays

Zhang, Yao; Duanmu, Qingduo; Yu, Feng-yuan; Liang, Yong-zhao; Chai, Jin; Wang, Guo-zheng; Yang, Ji-kai

2013-08-01

The application fields of high aspect ratio Si microchannel arrays have increased considerably, for example, Si microchannel plates, MEMS devices and so on. By the method of photo-electrochemical etching (PEC), Si microchannel arrays are prepared using n-Si wafer covered by anti-corrosion layers and initiation array pits. The dark current intensity curve of an n-type silicon wafer was presented in aqueous HF. The relationship among temperature, etching voltage and carrier transportation was presented. The influences of temperature and etching voltage on the surface morphology of silicon microchannel arrays were researched. The perfect Si microchannel arrays structure with the pore depth of 297 μm, the pore size of 3 μm and the aspect ratio of 99 was obtained by the method of reducing etching voltage gradually.

14. Preparing magnetic yttrium iron garnet nanodot arrays by ultrathin anodic alumina template on silicon substrate

Zheng, Hui; Han, Mangui, E-mail: han-mangui@yahoo.com; Deng, Longjiang [National Engineering Research Center of Electromagnetic Radiation Control Materials, University of Electronic Science and Technology of China, Chengdu 610054 (China); Zheng, Liang; Zheng, Peng; Qin, Huibin [Institute of Electron Device and Application, Hangzhou Dianzi University, Hangzhou 310008 (China); Wu, Qiong [Magnetism Key Laboratory of Zhejiang Province, China Jiliang University, Hangzhou 310018 (China)

2015-08-10

Ultrahigh density periodically ordered magnetic yttrium iron garnet (Y{sub 3}Fe{sub 5}O{sub 12}, YIG) nanodot arrays have been prepared by pulsed laser deposition through an ultrathin alumina mask (UTAM). UTAM having periodically ordered circularly shaped holes with 350 nm in diameter, 450 nm in inter-pore distance, and 700 nm in height has been prepared on silicon substrate. Furthermore, the microstructure and magnetic properties of YIG nanodot arrays have been characterized. Nanodot arrays with a sharp distribution in diameter centered at 340 nm with standard deviation of 10 nm have been fabricated. Moreover, typical hysteresis loops and ferromagnetic resonance spectra in in-plane and out-of-plane revealed that this unique structure greatly influences the magnetics properties of YIG. First, coercivity of YIG nanodot arrays in in-plane was increased about from 15 Oe of YIG films to 500 Oe. Then, the degree of uniformity about nanodot height decided that two or more resonance peaks in out-of-plane were detected in the spectra. The peak-to-peak linewidth values were about 94 Oe and 40 Oe in the parallel and perpendicular directions, respectively, which indicated that the values were larger by the two-magnon scattering. Consequently, this pattering method creates opportunities for studying physics in oxide nanomagnets and may be applied in spin-wave devices.

15. A low-profile three-dimensional neural probe array using a silicon lead transfer structure

Cheng, Ming-Yuan; Je, Minkyu; Tan, Kwan Ling; Lim Tan, Ee; Lim, Ruiqi; Yao, Lei; Li, Peng; Park, Woo-Tae; Phua, Eric Jian Rong; Lip Gan, Chee; Yu, Aibin

2013-09-01

This paper presents a microassembly method for low-profile three-dimensional probe arrays for neural prosthesis and neuroscience applications. A silicon (Si) lead transfer structure, Si interposer, is employed to form electrical connections between two orthogonal planes—the two dimensional probes and the dummy application-specific integrated circuit (ASIC) chip. In order to hold the probe array and facilitate the alignment of probes during assembly, a Si platform is designed to have through-substrate slots for the insertion of probes and cavities for holding the Si interposers. The electrical interconnections between the probes and the dummy ASIC chip are formed by solder reflow, resulting in greatly improved throughput in the proposed assembly method. Moreover, since the backbone of the probe can be embedded inside the cavity of the Si platform, the profile of the probe array above the cortical surface can be controlled within 750 µm. This low-profile allows the probe array not to touch the skull after it is implanted on the brain. The impedance of the assembled probe is also measured and discussed.

16. A low-profile three-dimensional neural probe array using a silicon lead transfer structure

This paper presents a microassembly method for low-profile three-dimensional probe arrays for neural prosthesis and neuroscience applications. A silicon (Si) lead transfer structure, Si interposer, is employed to form electrical connections between two orthogonal planes—the two dimensional probes and the dummy application-specific integrated circuit (ASIC) chip. In order to hold the probe array and facilitate the alignment of probes during assembly, a Si platform is designed to have through-substrate slots for the insertion of probes and cavities for holding the Si interposers. The electrical interconnections between the probes and the dummy ASIC chip are formed by solder reflow, resulting in greatly improved throughput in the proposed assembly method. Moreover, since the backbone of the probe can be embedded inside the cavity of the Si platform, the profile of the probe array above the cortical surface can be controlled within 750 µm. This low-profile allows the probe array not to touch the skull after it is implanted on the brain. The impedance of the assembled probe is also measured and discussed. (paper)

17. Monolithic arrays of silicon drift detectors for medical imaging applications and related CMOS readout electronics

Fiorini, C. [Politecnico di Milano, Dipartimento di Elettronica e Informazione, Milan (Italy) and INFN, Sezione di Milano, Milan (Italy)]. E-mail: carlo.fiorini@polimi.it; Longoni, A. [Politecnico di Milano, Dipartimento di Elettronica e Informazione, Milan (Italy); INFN, Sezione di Milano, Milan (Italy); Porro, M. [Politecnico di Milano, Dipartimento di Ingegneria Nucleare, Milan (Italy); INFN, Sezione di Milano, Milan (Italy); Perotti, F. [Istituto di Astrofisica Spaziale e Fisica Cosmica - INAF, Milan (Italy); Lechner, P. [PNSensors, Munich (Germany); Strueder, L. [MPI fuer Extraterrestrische Physik Halbleiterlabor, Munich (Germany)

2006-05-01

Monolithic arrays of Silicon Drift Detectors (SDDs) have been recently proposed to be used with scintillators for high-position-resolution {gamma}-ray imaging applications. Thanks to the low electronics noise due to the small value of the output capacitance, the SDD offers better performances with respect to conventional photodiodes of the same geometry. We show the results achieved with a small monolithic array of SDDs, each one with a front-end JFET integrated at its center, used as photodetector in a first prototype of Anger Camera. An intrinsic resolution better than 200 {mu}m has been achieved with this prototype. Moreover, we describe a new monolithic array of SDDs composed of 77 single hexagonal units, each one with an active area of 8.7 mm{sup 2}, for a total active area of the device of 6.7 cm{sup 2}. Finally, the basic principles and the first results of the CMOS readout chip specifically designed for the readout of the signals from SDDs arrays are presented.

18. Monolithic arrays of silicon drift detectors for medical imaging applications and related CMOS readout electronics

Monolithic arrays of Silicon Drift Detectors (SDDs) have been recently proposed to be used with scintillators for high-position-resolution γ-ray imaging applications. Thanks to the low electronics noise due to the small value of the output capacitance, the SDD offers better performances with respect to conventional photodiodes of the same geometry. We show the results achieved with a small monolithic array of SDDs, each one with a front-end JFET integrated at its center, used as photodetector in a first prototype of Anger Camera. An intrinsic resolution better than 200 μm has been achieved with this prototype. Moreover, we describe a new monolithic array of SDDs composed of 77 single hexagonal units, each one with an active area of 8.7 mm2, for a total active area of the device of 6.7 cm2. Finally, the basic principles and the first results of the CMOS readout chip specifically designed for the readout of the signals from SDDs arrays are presented

19. Evaluation of Matrix9 silicon photomultiplier array for small-animal PET

Purpose: The MatrixSL-9-30035-OEM (Matrix9) from SensL is a large-area silicon photomultiplier (SiPM) photodetector module consisting of a 3 × 3 array of 4 × 4 element SiPM arrays (total of 144 SiPM pixels) and incorporates SensL’s front-end electronics board and coincidence board. Each SiPM pixel measures 3.16 × 3.16 mm2 and the total size of the detector head is 47.8 × 46.3 mm2. Using 8 × 8 polished LSO/LYSO arrays (pitch 1.5 mm) the performance of this detector system (SiPM array and readout electronics) was evaluated with a view for its eventual use in small-animal positron emission tomography (PET). Methods: Measurements of noise, signal, signal-to-noise ratio, energy resolution, flood histogram quality, timing resolution, and array trigger error were obtained at different bias voltages (28.0–32.5 V in 0.5 V intervals) and at different temperatures (5 °C–25 °C in 5 °C degree steps) to find the optimal operating conditions. Results: The best measured signal-to-noise ratio and flood histogram quality for 511 keV gamma photons were obtained at a bias voltage of 30.0 V and a temperature of 5 °C. The energy resolution and timing resolution under these conditions were 14.2% ± 0.1% and 4.2 ± 0.1 ns, respectively. The flood histograms show that all the crystals in the 1.5 mm pitch LSO array can be clearly identified and that smaller crystal pitches can also be resolved. Flood histogram quality was also calculated using different center of gravity based positioning algorithms. Improved and more robust results were achieved using the local 9 pixels for positioning along with an energy offset calibration. To evaluate the front-end detector readout, and multiplexing efficiency, an array trigger error metric is introduced and measured at different lower energy thresholds. Using a lower energy threshold greater than 150 keV effectively eliminates any mispositioning between SiPM arrays. Conclusions: In summary, the Matrix9 detector system can resolve

20. Improved photo-stability of silicon nanobelt arrays by atomic layer deposition for efficient photocatalytic hydrogen evolution

Bao, Xiao-Qing; Liu, Lifeng

2014-12-01

Silicon nanostructures have recently drawn great interest for use as photocathodes to produce hydrogen through water photoelectrolysis. Despite the high photocurrent observed, nanostructured Si photocathodes usually exhibit poor photo-stability in aqueous solution and rapidly deactivate. Herein, we report that by coating a thin titania protection layer using atomic layer deposition (ALD), the photo-stability of silicon nanobelt arrays fabricated by metal assisted chemical etching can be markedly improved. The photocurrent loss of the silicon nanobelt array photoelectrode coated with a 3 nm titania layer is found to be much lower than that of the electrode without a titania coating. We also demonstrate that the 3 nm titania coated Si nanobelt arrays can sustain more than twelve hours without a significant loss in photocurrent under operation conditions before it eventually fails. The possible failure mechanism is preliminarily investigated.

1. Fabrication of porous silicon by metal-assisted etching using highly ordered gold nanoparticle arrays.

Scheeler, Sebastian P; Ullrich, Simon; Kudera, Stefan; Pacholski, Claudia

2012-01-01

A simple method for the fabrication of porous silicon (Si) by metal-assisted etching was developed using gold nanoparticles as catalytic sites. The etching masks were prepared by spin-coating of colloidal gold nanoparticles onto Si. An appropriate functionalization of the gold nanoparticle surface prior to the deposition step enabled the formation of quasi-hexagonally ordered arrays by self-assembly which were translated into an array of pores by subsequent etching in HF solution containing H2O2. The quality of the pattern transfer depended on the chosen preparation conditions for the gold nanoparticle etching mask. The influence of the Si surface properties was investigated by using either hydrophilic or hydrophobic Si substrates resulting from piranha solution or HF treatment, respectively. The polymer-coated gold nanoparticles had to be thermally treated in order to provide a direct contact at the metal/Si interface which is required for the following metal-assisted etching. Plasma treatment as well as flame annealing was successfully applied. The best results were obtained for Si substrates which were flame annealed in order to remove the polymer matrix - independent of the substrate surface properties prior to spin-coating (hydrophilic or hydrophobic). The presented method opens up new resources for the fabrication of porous silicon by metal-assisted etching. Here, a vast variety of metal nanoparticles accessible by well-established wet-chemical synthesis can be employed for the fabrication of the etching masks. PMID:22876790

2. Gold nano-island arrays on silicon as SERS active substrate for organic molecule detection

Gold islands forming highly controlled arrays have been fabricated by two potential step electrochemical deposition method using nanopatterned Si surface templates. In the present work, the Raman scattering studies realized using 11-mercaptoundecanoic probe molecule showed that such structures exhibit an enhanced Raman signal compared with nanostructured physical deposited thin gold film on flat silicon substrate and can be valued as surface-enhanced Raman scattering substrates. Besides the more appropriate management of nano-island arrays distribution, the high ratio of their Raman signals can be explain by the epitaxial-like growth mechanism of the metallic nano-islands, clearly showed by X-ray diffraction studies. Furthermore, the substrates enabled reproducibility and stability detection due to the chemically assembling of organothiol molecules, the X-ray photoelectron spectroscopy studies confirming formation of the thiolate species which corresponds to Au-S bonds, and also, the unwanted ‘hot-spots’ are missing, which make them suitable for high sensitivity biosensing applications. - Highlights: • Gold nano-islands are electrochemical deposited on nanopatterned silicon. • The X-ray diffraction studies revealed the epitaxial-like growth mechanism. • Enhanced Raman signal of Au nano-islands was observed compared with Au nano-film

3. Directing polyallylamine adsorption on microlens array patterned silicon for microarray fabrication.

Saini, Gaurav; Gates, Richard; Asplund, Matthew C; Blair, Steve; Attavar, Sachin; Linford, Matthew R

2009-06-21

The selective adsorption of reagents is often essential for bioarray and lab-on-a-chip type devices. As the starting point for a bioarray, alkyl monolayer terminated silicon shards were photopatterned in a few nanoseconds with thousands of wells (spots) using an optical element, a microlens array. Polyallylamine (PAAm), a primary amine containing polymer, adsorbed with little selectivity to the spots, i.e., silicon oxide, over the hydrophobic background. However, at appropriate concentrations, addition of a cationic surfactant to the PAAm deposition solution, cetyltrimethylammonium chloride, prevented the nonspecific adsorption of PAAm onto the hydrophobic monolayer, while directing it effectively to the active spots on the device. A nonionic surfactant was less effective in preventing the nonspecific adsorption of PAAm onto the hydrophobic monolayer. The localized reactions/interactions of adsorbed PAAm with four species that are useful for bioconjugate chemistry: glutaric anhydride, phenylenediisothiocyanate, biotin NHS ester, and an oligonucleotide (DNA) were shown in the spots of an array. The reactivity of PAAm was further demonstrated with an isocyanate. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) played an important role in confirming selective surface reactivity and adsorption. X-ray photoelectron spectroscopy (XPS), spectroscopic ellipsometry, and wetting confirmed PAAm reactivity on planar substrates. PMID:19495464

4. Photoemission and photo-field-emission from photocathodes with arrays of silicon tips under continuous and pulsed lasers action

The electron machines's development and improvement go through the discovery of new electron sources of high brightness. After reminding the interests in studying silicon cathodes with array of tips as electron sources, I describe, in the three steps model, the main phenomenological features related to photoemission and photoemission and photo-field-emission from a semi-conductor. the experimental set-ups used for the measurements reported in chapter four, five and six are described in chapter three. In chapter three. In chapter four several aspects of photo-field-emission in continuous and nanosecond regimes, studied on the Clermont-Ferrand's test bench are tackled. We have measured quantum efficacies of 0.4 percent in the red (1.96 eV). Temporal responses in the nanoseconds range (10 ns) were observed with the Nd: YLF laser. With the laser impinging at an oblique angle we obtained ratios of photocurrent to dark current of the order of twenty. The issue of the high energy extracted photocurrent saturation is addressed and I give a preliminary explanation. In collaboration with the L.A.L. (Laboratoire de l'Accelerateur Lineaire) some tests with shortened pulsed laser beam (Nd: YAG laser 35 ps) were performed. Satisfactory response times have been obtained within the limitation of the scope (400 ps). (authors). 101 refs. 93 figs., 27 tabs., 3 photos., 1 append

5. Synthesis, Characterization and Kinetics of Epitaxial-Oriented Silicon Nanowire Arrays on Si Substrates

Wang, Z. L.; Bao, J. K.; Wan, Y. T.; Xia, W. W.; Wang, Y. W.; Sha, J.

The fabrication of vertical-oriented, high aspect ratio silicon nanowires (SiNWs) with controllable density and length is of interest for the development of nanowire-based electronics and photovoltaic devices. Here we reported a both simple and economical method for synthesizing large-area epitaxial-oriented SiNW arrays, which was achieved on the Si (111) substrates by Au catalyzed vapor-liquid-solid mechanism using the conventional chemical vapor deposition furnace system. Their morphologies and microstructures were investigated with scanning electron microscopy and transmission electron microscopy, respectively. The results showed that most of nanowires were vertically grown on substrates, their density and length can be well controlled. As-grown SiNW is composed of a single crystalline silicon core and a thin amorphous silicon oxide coating layer. Furthermore, their growth kinetics was discussed in detail. It indicates that there are both the substrate-nanowire Si adatom surface diffusion and the slight radial growth during the upgrowth of nanowire, and besides, the migration of Au on the sidewall of nanowire was also found for such epitaxial-oriental SiNWs.

6. Design of a prototype microchannel plate detector with cooled amorphous silicon array readout for neutron radiography

High-performance large-area imaging detectors for fast neutrons in the 5-14 MeV energy range do not exist at present. The aim of this project is to combine microchannel plates or MCPs (or similar electron multiplication structures) traditionally used in image intensifiers and X-ray detectors with amorphous silicon pixel arrays to produce a composite converter and intensifier position-sensitive imaging system. This detector will provide an order of magnitude improvement in image resolution when compared with current millimetre resolution limits obtained using phosphor- or scintillator-based hydrogen-rich converters. In this study the detection of fast neutrons is based on neutron capture in silicon rather than proton recoil in hydrogen-rich converters. This will reduce the effect that light spreading has on image resolution when using conventional phosphor-based converters. The threshold in the silicon capture cross-section will reduce the effect of neutron scatter on the detectability of small features in fast neutron radiographs. In this study we highlight the prototype detector design, present its main advantages and the current status of the detector build phase

7. Subwavelength silicon through-hole arrays as an all-dielectric broadband terahertz gradient index metamaterial

Structuring at subwavelength scales brings out artificial media with anomalous optical features called metamaterials. All-dielectric metamaterials have high potential for practical applications over the whole electromagnetic spectrum owing to low loss and optical isotropy. Here, we report subwavelength silicon through-hole arrays as an all-dielectric gradient index metamaterial with broadband THz operation. The unit cell consists of a single subwavelength through-hole on highly resistive monocrystalline silicon. Depending on the fill-factor and period, the effective index was linearly modulated at 0.3–1.6 THz. The experimental results also demonstrate silicon gradient refractive index (Si-GRIN) lenses with parabolic index profiles through the spatial modification of a single unit cell along the radial direction. Si-GRIN lenses either focus 0.4–1.6 THz beam to the diffraction-limit or serve as a flat and thin solid immersion lens on the backside of THz photoconductive antenna for highly efficient pulse extraction. This all-dielectric gradient index metamaterial opens up opportunities for integrated THz GRIN optics.

8. Contact angle anomalies indicate that surface-active eluates from silicone coatings inhibit the adhesive mechanisms of fouling organisms.

Meyer, Anne; Baier, Robert; Wood, Christina Darkangelo; Stein, Judith; Truby, Kathryn; Holm, Eric; Montemarano, Jean; Kavanagh, Christopher; Nedved, Brian; Smith, Celia; Swain, Geoff; Wiebe, Deborah

2006-01-01

Silicone coatings with critical surface tensions (CST) between 20 and 30 mN m-1 more easily release diverse types of biofouling than do materials of higher and lower CST. Oils added to these coatings selectively further diminish the attachment strengths of different marine fouling organisms, without significantly modifying the initial CST. In a search for the mechanisms of this improved biofouling resistance, the interfacial instabilities of four silicone coatings were characterised by comprehensive contact angle analyses, using up to 12 different diagnostic fluids selected to mimic the side chain chemistries of the common amino acids of bioadhesive proteins. The surfaces of painted steel test panels were characterised both before and after exposure to freshwater, brackish water, and seawater over periods ranging from 9 months to nearly 4 years. Contact angle measurements demonstrated significant surface activity of the oil-amended coatings both before and after long-term underwater exposure. The surface activity of the control (coating without oil) increased as a result of underwater exposure, consistent with mild surface chain scission and hydrolysis imparting a self-surfactancy to the coating and providing a weak boundary layer promoting continuing easy release of attaching foulants. Coatings with additives that most effectively reduced biofouling showed both initial and persistent contact angle anomalies for the test liquid, thiodiglycol, suggesting lower-shear biofouling release mechanisms based upon diminished bioadhesive crosslinking by interfering with hydrogen- and sulfhydryl bonds. Swelling of the silicone elastomeric coatings by hydrocarbon fluids was observed for all four coatings, before and after immersion. PMID:17178574

9. OPTIMAL BEAM STEERING ANGLES OF A SENSOR ARRAY FOR A MULTIPLE SOURCE SCENARIO

Sanghyouk Cho

2016-01-01

Full Text Available We present the gradient and Hessian of the trace of the multivariate Cramér-Rao bound (CRB formula for unknown impinging angles of plane waves with non-unitary beamspace measurements,. These gradient and Hessian can be used to find the optimal beamspace transformation matrix, i.e., the optimum beamsteering angles, using the Newton-Raphson iteration. These trace formulas are particularly useful to deal with the multiple source senario. We also show the mean squred error (MSE performance gain of the optimally steered beamspace measurements compared with the usuall DFT steered measurements, when the angle of arrivals (AOAs are estimated with stochastic maximum likelihood (SMLE algorithm.

10. Comparative anomalous small-angle X-ray scattering study of hotwire and plasma grown amorphous silicon-germanium alloys

Goerigk, G.; Williamson, D. L.

2001-01-01

The nanostructure of hydrogenated amorphous silicon-germanium alloys, a-Si1-xGex:H, prepared by the hotwire deposition technique (x=0.06-0.79) and by the plasma enhanced chemical vapor deposition technique (x=0 and 0.50) was analyzed by anomalous small-angle x-ray scattering experiments. For all alloys with x >0 the Ge component was found to be inhomogeneously distributed with correlation lengths of about 1 nm. A systematic increase of the separated scattering was found due to the increasing ...

11. Impact ionization in high resistivity silicon induced by an intense terahertz field enhanced by an antenna array

Tarekegne, Abebe Tilahun; Iwaszczuk, Krzysztof; Zalkovskij, Maksim;

2015-01-01

antenna array. The carrier multiplication is probed by the frequency shift of the resonance of the antenna array due to the change of the local refractive index of the substrate. Experimental results and simulations show that the carrier density in silicon increases by over seven orders of magnitude in......We report on the observation of ultrafast impact ionization and carrier generation in high resistivity silicon induced by intense subpicosecond terahertz transients. Local terahertz peak electric fields of several MV cm−1 are obtained by field enhancement in the near field of a resonant metallic...

12. Imaging performance of silicon photomultipliers coupled to BGO and CsI:Na arrays

The aim of this study is to investigate the imaging performance of a silicon photomultiplier array (ArraySL-4) photodetector for possible PET and potentially SPECT applications using BGO and CsI(Na) pixellated scintillators. Our main objectives are: i) the comparison of the ArraySL-4 to the older version SensL's SPMArray4 photo detector in terms of energy resolution and peak to valley ratio of a row profile in the flood image and ii) the study of the effect of different coupling schemes using ultra transmitting glass windows of various thicknesses. We acquired raw images from two pixellated scintillators (BGO with 2 × 2×5 mm3 and CsI:Na with 1 × 1×5 mm3 pixel sizes) irradiated with 511 keV and 1274.5 keV γ-rays from a 22Na source. The SiPM array detector allowed the clear visualization of the discrete 2 × 2 mm2 pixellated BGO and 1 × 1 mm2 CsI:Na scintillator elements at room temperature (no cooling). The energy resolution of the new SensL ArraySL-4 detector for the 2 × 2×5 mm3 BGO pixellated scintillator array is improved for rather 6 percentage points (energy resolution improvement equal to 22%) and the peak to valley ratio is measured higher for both scintillator arrays (for BGO 68% (1.7 × ) and for CsI:Na 154% (2.5 × )) compared with SPMArray4. The clear identification of the 1 × 1 mm2 CsI:Na scintillator elements provides evidence that the combination of those SiPMs with even smaller arrays can be used as an efficient imaging detector module. Optical coupling significantly improves image uniformity, while the use of BK7 ultra transmitting glass window with 1.35 mm thickness provided the best measure energy resolution equal to 21.5%

13. The effects of oxygen plasma and humidity on surface roughness, water contact angle and hardness of silicon, silicon dioxide and glass

For heterogeneous integration in many More-than-Moore applications, surface preparation is the key step to realizing well-bonded multiple substrates for electronics, photonics, fluidics and/or mechanical components without a degradation in performance. Therefore, it is critical to understand how various processing and environmental conditions affect their surface properties. In this paper, we investigate the effects of oxygen plasma and humidity on some key surface properties such as the water contact angle, roughness and hardness of three materials: silicon (Si), silicon dioxide (SiO2) and glass, and their impact on bondability. The low surface roughness, high surface reactivity and high hydrophilicity of Si, SiO2 and glass at lower activation times can result in better bondability. Although, the surface reactivity of plasma-ambient-humidity-treated Si and SiO2 is considerably reduced, their reduction of roughness and increase of hydrophilicity may enable good bonding at low temperature heating due to augmented hydroxyl groups. The decrease of hardness of Si and SiO2 with increased activation time is attributed to higher surface roughness and the formation of amorphous layers of Si. While contact angle and surface roughness results show a correlation with bondability, the role of hardness on bondability requires further investigation. (paper)

14. BBB leakage, astrogliosis, and tissue loss correlate with silicon microelectrode array recording performance.

Nolta, Nicholas F; Christensen, Michael B; Crane, Paul D; Skousen, John L; Tresco, Patrick A

2015-01-01

The clinical usefulness of brain machine interfaces that employ penetrating silicon microelectrode arrays is limited by inconsistent performance at chronic time points. While it is widely believed that elements of the foreign body response (FBR) contribute to inconsistent single unit recording performance, the relationships between the FBR and recording performance have not been well established. To address this shortfall, we implanted 4X4 Utah Electrode Arrays into the cortex of 28 young adult rats, acquired electrophysiological recordings weekly for up to 12 weeks, used quantitative immunohistochemical methods to examine the intensity and spatial distribution of neural and FBR biomarkers, and examined whether relationships existed between biomarker distribution and recording performance. We observed that the FBR was characterized by persistent inflammation and consisted of typical biomarkers, including presumptive activated macrophages and activated microglia, astrogliosis, and plasma proteins indicative of blood-brain-barrier disruption, as well as general decreases in neuronal process distribution. However, unlike what has been described for recording electrodes that create only a single penetrating injury, substantial brain tissue loss generally in the shape of a pyramidal lesion cavity was observed at the implantation site. Such lesions were also observed in stab wounded animals indicating that the damage was caused by vascular disruption at the time of implantation. Using statistical approaches, we found that blood-brain barrier leakiness and astrogliosis were both associated with reduced recording performance, and that tissue loss was negatively correlated with recording performance. Taken together, our data suggest that a reduction of vascular damage at the time of implantation either by design changes or use of hemostatic coatings coupled to a reduction of chronic inflammatory sequela will likely improve the recording performance of high density

15. A Stable Flexible Silicon Nanowire Array as Anode for High-Performance Lithium-ion Batteries

Highlights: • A flexible SiNW array in PDMS structure is designed and fabricated as Li-ion battery anode material. • The aggregation and fracture of SiNWs are alleviated by the flexible PDMS skeleton during the process of charge and discharge. • The loose SiO2 shells coating on the SiNWscould form the protective layer in charge/discharge. • The as-obtain flexible SiNW array/PDMS composite exhibits a much better cycling stability. - Abstract: A Silicon nanowire (SiNW) array inserted into flexible poly-dimethylsiloxane (SiNW array/PDMS) composite structure as anode with high capacity and long-term cycling stability is synthesized by a cost-effective and scalable method. In this structure, the aggregation and fracture of SiNWs are alleviated by the flexible PDMS skeleton. Act as the main active component, the SiNWs are coated by loose SiO2 shells. These loose SiO2 shells not only provide space for the large volume changes of SiNW, but also react with the electrolyte and form the stable protective layer during the processes of the lithiation and delithiation. These two functions could improve the cycling stability and columbic efficiency of the SiNWs. The as-obtain flexible SiNW array/PDMS composite structure exhibits excellent long-term cycling stability with a specific capacity of 887.2 mA·h·g−1 and capacity retention of ∼83.4% over 350 cycles at 0.5 C rate compared with the fifteenth cycle. The design of this new structure provides a potential way for developing other functional composite materials

16. The status of lightweight photovoltaic space array technology based on amorphous silicon solar cells

Hanak, Joseph J.; Kaschmitter, Jim

1991-01-01

Ultralight, flexible photovoltaic (PV) array of amorphous silicon (a-Si) was identified as a potential low cost power source for small satellites. A survey was conducted of the status of the a-Si PV array technology with respect to present and future performance, availability, cost, and risks. For existing, experimental array blankets made of commercial cell material, utilizing metal foil substrates, the Beginning of Life (BOL) performance at Air Mass Zero (AM0) and 35 C includes total power up to 200 W, power per area of 64 W/sq m and power per weight of 258 W/kg. Doubling of power per weight occurs when polyimide substrates are used. Estimated End of Life (EOL) power output after 10 years in a nominal low earth orbit would be 80 pct. of BOL, the degradation being due to largely light induced effects (-10 to -15 pct.) and in part (-5 pct.) to space radiation. Predictions for the year 1995 for flexible PV arrays, made on the basis of published results for rigid a-Si modules, indicate EOL power output per area and per weight of 105 W/sq m and 400 W/kg, respectively, while predictions for the late 1990s based on existing U.S. national PV program goals indicate EOL values of 157 W/sq m and 600 W/kg. Cost estimates by vendors for 200 W ultralight arrays in volume of over 1000 units range from $100/watt to$125/watt. Identified risks include the lack of flexible, space compatible encapsulant, the lack of space qualification effort, recent partial or full acquisitions of US manufacturers of a-Si cells by foreign firms, and the absence of a national commitment for a long range development program toward developing of this important power source for space.

17. Development of silicon monolithic arrays for dosimetry in external beam radiotherapy

Bisello, Francesca, E-mail: francesca.bisello@iba-group.com [IBA Dosimetry GmbH, Schwarzenbruck (Germany); Friedrich-Alexander Universität Erlangen—Nürnberg, Erlangen (Germany); Menichelli, David [IBA Dosimetry GmbH, Schwarzenbruck (Germany); Scaringella, Monica [University of Florence, Firenze (Italy); INFN—Florence Division, Sesto Fiorentino (Italy); Talamonti, Cinzia; Zani, Margherita; Bucciolini, Marta [University of Florence, Firenze (Italy); Azienda Ospedaliera Unversitaria Careggi, Firenze (Italy); Bruzzi, Mara [University of Florence, Firenze (Italy); INFN—Florence Division, Sesto Fiorentino (Italy)

2015-10-01

New tools for dosimetry in external beam radiotherapy have been developed during last years in the framework of the collaboration among the University of Florence, INFN Florence and IBA Dosimetry. The first step (in 2007) was the introduction in dosimetry of detector solutions adopted from high energy physics, namely epitaxial silicon as the base detector material and a guard ring in diode design. This allowed obtaining state of the art radiation hardness, in terms of sensitivity dependence on accumulated dose, with sensor geometry particularly suitable for the production of monolithic arrays with modular design. Following this study, a 2D monolithic array has been developed, based on 6.3×6.3 cm{sup 2} modules with 3 mm pixel pitch. This prototype has been widely investigated and turned out to be a promising tool to measure dose distributions of small and IMRT fields. A further linear array prototype has been recently design with improve spatial resolution (1 mm pitch) and radiation hardness. This 24 cm long device is constituted by 4×64 mm long modules. It features low sensitivity changes with dose (0.2%/kGy) and dose per pulse (±1% in the range 0.1–2.3 mGy/pulse, covering applications with flattened and unflattened photon fields). The detector has been tested with very satisfactory results as a tool for quality assurance of linear accelerators, with special regards to small fields, and proton pencil beams. In this contribution, the characterization of the linear array with unflattened MV X-rays, {sup 60}Co radiation and 226 MeV protons is reported. - Highlights: • A silicon monolithic 1D array with 1 mm pixel pitch was developed. • The detector was characterized with {sup 60}Co, unflattened MV X-rays, 226 MeV protons. • Dose linearity in clinical relevance range and dose profiles were measured. • The detector performs good agreement with reference detectors. • The technology is suitable in dose profiling in MV X-ray and proton therapy.

18. Fabrication of 721-pixel silicon lens array of a microwave kinetic inductance detector camera

Mitsui, Kenji; Nitta, Tom; Okada, Norio; Sekimoto, Yutaro; Karatsu, Kenichi; Sekiguchi, Shigeyuki; Sekine, Masakazu; Noguchi, Takashi

2015-04-01

We have been developed a lens-integrated superconducting camera for millimeter and submillimeter astronomy. High-purity silicon (Si) is suitable for the lens array of the microwave kinetic inductance detector camera due to its high refractive index and low dielectric loss at low temperatures. The camera is an antenna-coupled Al coplanar waveguide on a Si substrate. Thus the lens and the device are made of the same material. We report a fabrication method of a 721-pixel Si lens array with an antireflection (AR) coating. The Si lens array was fabricated with an ultraprecision cutting machine. It uses TiAlN-coated carbide end mills attached with a high-speed spindle. The shape accuracy was less than 50 μm peak-to-valley and the surface roughness was arithmetic average roughness (Ra) of 1.8 μm. The mixed epoxy was used as an AR coating to adjust the refractive index. It was shaved to yield a thickness of 185 μm for 220 GHz. Narrow grooves were made between the lenses to prevent cracking due to the different thermal expansion coefficients of Si and the epoxy. The surface roughness of the AR coating was Ra of 2.4 to 4.2 μm.

19. Simulation Analysis on Photoelectric Conversion Characteristics of Silicon Nanowire Array Photoelectrodes

Zhao, Yong; Yu, Jin; Fang, Li-Guang; Zheng, Jun; Wang, Hui-Qin; Yuan, Ji-Ren; Wu, Shaolong; Cheng, Guo-An

2015-06-01

Semiconductor nanowire photoelectrochemical cells have attracted extensive attention in the light-conversion field owing to the low-cost preparation, excellent optical absorption, and short distance of carrier collection. Although there are numbers of experimental investigations to improve the device performance, the understanding of the detailed process of photoelectric conversion needs to be further improved. In this work, a thorough optoelectronic simulation is employed to figure out how the nanowire diameter, doping concentration, and illumination wavelength affect the photoelectric conversion characteristics of the silicon nanowire array photoelectrodes. We find that two balances should be carefully weighted between optical absorption and photogenerated-carrier collection, along with between short-circuit photocurrent density and open-circuit voltage. For the small-diameter nanowire array photoelectrodes, the overall absorption is higher than that of the larger-diameter ones with the most contribution from the nanowires. However, the substrate shows increasing absorption with increasing illumination wavelength. Higher doping density leads to a larger open-circuit voltage; while lower doping density can guarantee a relatively higher short-circuit photocurrent. To obtain high-light-conversion-efficiency photoelectrodes, the doping density should be carefully chosen with considerations of illumination wavelength and surface recombination. Suppressing the surface recombination velocity can effectively enhance the short-circuit photocurrent (open-circuit voltage) for the lightly (heavily) doped nanowire array photoelectrodes. Our systematical results provide a theoretical guidance for the photoelectrochemical devices based on semiconductor nanostructures.

20. Aluminum oxide passivated radial junction sub-micrometre pillar array textured silicon solar cells

We report radial, p–n junction, sub-micrometre, pillar array textured solar cells, fabricated on an n-type Czochralski silicon wafer. Relatively simple processing schemes such as metal-assisted chemical etching and spin on dopant techniques were employed for the fabrication of the proposed solar cells. Atomic layer deposition (ALD) grown aluminum oxide (Al2O3) was employed as a surface passivation layer on the B-doped emitter surface. In spite of the fact that the sub-micrometre pillar array textured surface has a relatively high surface-to-volume ratio, we observed an open circuit voltage (VOC) and a short circuit current density (JSC) as high as 572 mV and 29.9 mA cm−2, respectively, which leads to a power conversion efficiency in excess of 11.30%, for the optimized structure of the solar cell described herein. Broadband omnidirectional antireflection effects along with the light trapping property of the sub-micrometre, pillar array textured surface and the excellent passivation quality of the ALD-grown Al2O3 on the B-doped emitter surface were responsible for the enhanced electrical performance of the proposed solar cells. (paper)

1. Sensitive refractive index sensing with tunable sensing range and good operation angle-polarization-tolerance using graphene concentric ring arrays

A highly tunable refractive index sensor with excellent performance and good operation angle-polarization-tolerance is proposed and demonstrated numerically by means of the finite element method. The proposed sensor consists of a planar regular array of paired graphene concentric ring resonators sandwiched between a substrate and a sensing medium. Numerical calculation results show that a high sensitivity of 9.59 µm per refractive index unit and figure of merit of 5.82 can be reached for lower sensing medium refractive indices. The introduction of graphene in this sensor can enhance the absorption of biomolecules and make the sensing range actively tunable. Therefore, it can be conveniently used for possible detection of the refractive index variation of gases, liquids or mixed solutions. Also, we predict that a multi-channel sensor can be achieved by introducing several graphene concentric ring resonators into each unit cell of the array. (paper)

2. Symmetric and anti-symmetric magnetic resonances in double-triangle nanoparticle arrays fabricated via angle-resolved nanosphere lithography

Jian Pan

2011-12-01

Full Text Available We report experimentally that for a particular high-symmetry planar periodic arrangement of metal double-triangle nanoparticle arrays fabricated via angle resolved nanosphere lithography, both anti-symmetric and symmetric magnetic resonances can be explicitly excited at off-normal incidence. Further, we demonstrate that the underlying mechanism for the formation of these two modes is a result of direct interactions with the incident electric and magnetic fields, respectively. As a consequence, with increasing the incident angle there is a relatively small blue-shift in the transmission for the electric-field induced anti-symmetric mode, while a remarkable red-shift is observed for the magnetic-field induced symmetric mode.

3. Ordered array of ω particles in β-Ti matrix studied by small-angle X-ray scattering

Nanosized particles of ω phase in a β-Ti alloy were investigated by small-angle X-ray scattering using synchrotron radiation. We demonstrated that the particles are spontaneously weakly ordered in a three-dimensional cubic array along the 〈100〉-directions in the β-Ti matrix. The small-angle scattering data fit well to a three-dimensional short-range-order model; from the fit we determined the evolution of the mean particle size and mean distance between particles during ageing. The self-ordering of the particles is explained by elastic interaction between the particles, since the relative positions of the particles coincide with local minima of the interaction energy. We performed numerical Monte Carlo simulation of the particle ordering and we obtained a good agreement with the experimental data

4. Formation of Mach angle profiles during wet etching of silica and silicon nitride materials

Ghulinyan, M.; Bernard, M.; Bartali, R.; Pucker, G.

2015-12-01

In integrated circuit technology peeling of masking photoresist films is a major drawback during the long-timed wet etching of materials. It causes an undesired film underetching, which is often accompanied by a formation of complex etch profiles. Here we report on a detailed study of wedge-shaped profile formation in a series of silicon oxide, silicon oxynitride and silicon nitride materials during wet etching in a buffered hydrofluoric acid (BHF) solution. The shape of etched profiles reflects the time-dependent adhesion properties of the photoresist to a particular material and can be perfectly circular, purely linear or a combination of both, separated by a knee feature. Starting from a formal analogy between the sonic boom propagation and the wet underetching process, we model the wedge formation mechanism analytically. This model predicts the final form of the profile as a function of time and fits the experimental data perfectly. We discuss how this knowledge can be extended to the design and the realization of optical components such as highly efficient etch-less vertical tapers for passive silicon photonics.

5. Effect of acid vapor etching on morphological and opto-electric properties of flat silicon and silicon nanowire arrays: A comparative study

Amri, Chohdi; Ouertani, Rachid; Hamdi, Abderrahmen; Ezzaouia, Hatem

2016-03-01

In this paper, we report a comparative study between porous silicon (pSi) and porous silicon nanowires (pSiNWs). Acid Vapor Etching (AVE) treatment has been used to perform porous structure on flat Si and SiNWs array substrates respectively. SiNW structure is prepared by the widely used Silver catalyzed etching method. SEM and TEM images show that AVE treatment induces porous structure in the whole Si wafer and the SiNW sidewall. Comparatively to pSi, pSiNWs exhibit a low reflectivity in the whole spectral range which decreases with etching duration. However, the reflectivity of pSi changes with porous layer thickness. Both pSi and pSiNWs exhibit a significant PL peak situated at 2 eV. PL peaks are attributed to the quantum confinement effect in the silicon nanocrystallites (SiNCs). We discussed the significant enhancement in the peak intensities and a shift toward lower energy displayed in Raman spectra for both pSi and pSiNWs. We reported a correlative study of the AVE treatment effect on the minority carrier life time of flat silicon and SiNW arrays with the passivation effect of chemical induced silicon oxides highlighted by FTIR spectra.

6. Towards doubling solar harvests using wide-angle, broad-band microfluidic beam steering arrays.

DiDomenico, Leo D

2015-11-30

This paper introduces Microfluidic Beam Steering (MBS), which is a new technique for electronically steering light having multiple octaves of bandwidth, any polarization state and incidence from any direction of the sky without significant restrictions due to physical area, optical loss and power handling capacity. It is based on optical elements comprising both transparent solids and electronically controllable fluids to control Total Internal Reflection (TIR), refraction and/or diffraction from micro-structured surfaces within a transparent solid. A TIR-based MBS is discussed in the context of solar energy and its potential to significantly increase annual energy harvests from solar arrays situated on fixed areas like roofs. The advantages and challenges associated with analog and digital MBS systems are discussed and early-stage MBS hardware is demonstrated. Finally, an analytic model of sun-tracking is provided to formally establish the potential for MBS to increase annual solar energy harvests by approximately 45% more than conventional 0-Degree Of Freedom (0-DOF) solar arrays, 62% more than 1-DOF arrays and 233% more than 2-DOF arrays, all at 20% atmospheric aerosol scattering. PMID:26698790

7. A Silicon-Based Nanothin Film Solid Oxide Fuel Cell Array with Edge Reinforced Support for Enhanced Thermal Mechanical Stability.

Baek, Jong Dae; Yu, Chen-Chiang; Su, Pei-Chen

2016-04-13

A silicon-based micro-solid oxide fuel cell (μ-SOFC) with electrolyte membrane array embedded in a thin silicon supporting membrane, featuring a unique edge reinforcement structure, was demonstrated by utilizing simple silicon micromachining processes. The square silicon supporting membrane, fabricated by combining deep reactive ion etching and through-wafer wet etching processes, has thicker edges and corners than the center portion of the membrane, which effectively improved the mechanical stability of the entire fuel cell array during cell fabrication and cell operation. The 20 μm thick single crystalline silicon membrane supports a large number of 80 nm thick free-standing yttria-stabilized zirconia (YSZ) electrolytes. The fuel cell array was stably maintained at the open circuit voltage (OCV) of 1.04 V for more than 30 h of operation at 350 °C. A high peak power density of 317 mW/cm(2) was obtained at 400 °C. During a rigorous in situ thermal cycling between 150 and 400 °C at a fast cooling and heating rate of 25 °C/min, the OCV of the μ-SOFC recovered to its high value of 1.07 V without any drop caused by membrane failure, which justifies the superior thermal stability of this novel cell architecture. PMID:26990604

8. Microfabrication of an Implantable silicone Microelectrode array for an epiretinal prosthesis

Maghribi, M

2003-06-10

Millions of people suffering from diseases such as retinitis pigmentosa and macular degeneration are legally blind due to the loss of photoreceptor function. Fortunately a large percentage of the neural cells connected to the photoreceptors remain viable, and electrical stimulation of these cells has been shown to result in visual perception. These findings have generated worldwide efforts to develop a retinal prosthesis device, with the hope of restoring vision. Advances in microfabrication, integrated circuits, and wireless technologies provide the means to reach this challenging goal. This dissertation describes the development of innovative silicone-based microfabrication techniques for producing an implantable microelectrode array. The microelectrode array is a component of an epiretinal prosthesis being developed by a multi-laboratory consortium. This array will serve as the interface between an electronic imaging system and the human eye, directly stimulating retinal neurons via thin film conducting traces. Because the array is intended as a long-term implant, vital biological and physical design requirements must be met. A retinal implant poses difficult engineering challenges due to the size of the intraocular cavity and the delicate retina. Not only does it have to be biocompatible in terms of cytotoxicity and degradation, but it also has to be structurally biocompatible, with regard to smooth edges and high conformability; basically mimicking the biological tissue. This is vital to minimize stress and prevent physical damage to the retina. Also, the device must be robust to withstand the forces imposed on it during fabrication and implantation. In order to meet these biocompatibility needs, the use of non-conventional microfabrication materials such as silicone is required. This mandates the enhancement of currently available polymer-based fabrication techniques and the development of new microfabrication methods. Through an iterative process, devices

9. An Antireflective Nanostructure Array Fabricated by Nanosilver Colloidal Lithography on a Silicon Substrate

Park Seong-Je

2010-01-01

Full Text Available Abstract An alternative method is presented for fabricating an antireflective nanostructure array using nanosilver colloidal lithography. Spin coating was used to produce the multilayered silver nanoparticles, which grew by self-assembly and were transformed into randomly distributed nanosilver islands through the thermodynamic action of dewetting and Oswald ripening. The average size and coverage rate of the islands increased with concentration in the range of 50–90 nm and 40–65%, respectively. The nanosilver islands were critically affected by concentration and spin speed. The effects of these two parameters were investigated, after etching and wet removal of nanosilver residues. The reflection nearly disappeared in the ultraviolet wavelength range and was 17% of the reflection of a bare silicon wafer in the visible range.

10. Sensitive and Selective Detection of HIV-1 RRE RNA Using Vertical Silicon Nanowire Electrode Array

Lee, Jaehyung; Hong, Min-Ho; Han, Sanghun; Na, Jukwan; Kim, Ilsoo; Kwon, Yong-Joon; Lim, Yong-beom; Choi, Heon-Jin

2016-07-01

In this study, HIV-1 Rev response element (RRE) RNA was detected via an Au-coated vertical silicon nanowire electrode array (VSNEA). The VSNEA was fabricated by combining bottom-up and top-down approaches and then immobilized by artificial peptides for the recognition of HIV-1 RRE. Differential pulse voltammetry (DPV) analysis was used to measure the electrochemical response of the peptide-immobilized VSNEA to the concentration and types of HIV-1 RRE RNA. DPV peaks showed linearity to the concentration of RNA with a detection limit down to 1.513 fM. It also showed the clear different peaks to the mutated HIV-1 RRE RNA. The high sensitivity and selectivity of VSNEA for the detection of HIV-1 RRE RNA may be attributed to the high surface-to-volume ratio and total overlap diffusion mode of ions of the one-dimensional nanowire electrodes.

11. Growth of two-dimensional arrays of uncapped gold nanoparticles on silicon substrates

Anindya Das; Soma Das; A K Raychaudhuri

2008-06-01

A method of preparing large area patterned 2D arrays of uncapped gold (Au) nanoparticles has been developed. The pattern has been formed using self-assembly of uncapped Au nanoparticles. The Au nanoparticles were synthesized via toluene/water two phase systems using a reducing agent and colloidal solution of Au nanoparticles was produced. These nanoparticles have been prepared without using any kind of capping agent. Analysis by TEM showed discrete Au nanoparticles of 4 nm average diameter. AFM analysis also showed similar result. The TEM studies showed that these nanoparticles formed self-assembled coherent patterns with dimensions exceeding 500 nm. Spin coating on silicon substrate by suitably adjusting the speed can self-assemble these nanoparticles to lengths exceeding 1 m.

12. Sensitive and Selective Detection of HIV-1 RRE RNA Using Vertical Silicon Nanowire Electrode Array.

Lee, Jaehyung; Hong, Min-Ho; Han, Sanghun; Na, Jukwan; Kim, Ilsoo; Kwon, Yong-Joon; Lim, Yong-Beom; Choi, Heon-Jin

2016-12-01

In this study, HIV-1 Rev response element (RRE) RNA was detected via an Au-coated vertical silicon nanowire electrode array (VSNEA). The VSNEA was fabricated by combining bottom-up and top-down approaches and then immobilized by artificial peptides for the recognition of HIV-1 RRE. Differential pulse voltammetry (DPV) analysis was used to measure the electrochemical response of the peptide-immobilized VSNEA to the concentration and types of HIV-1 RRE RNA. DPV peaks showed linearity to the concentration of RNA with a detection limit down to 1.513 fM. It also showed the clear different peaks to the mutated HIV-1 RRE RNA. The high sensitivity and selectivity of VSNEA for the detection of HIV-1 RRE RNA may be attributed to the high surface-to-volume ratio and total overlap diffusion mode of ions of the one-dimensional nanowire electrodes. PMID:27448026

13. Microstructure and blue photoluminescence enhancement of silicon nanoporous pillar array embedded in ferroelectric barium strontium titanate

A silicon nanoporous pillar array (Si-NPA) with micrometer/nanometer hierarchical structure was fabricated by hydrothermal etching, followed by spin-coating barium strontium titanate (BST) on Si-NPA substrate. The photoluminescence (PL) spectra of the Si-NPA and BST/Si-NPA thin film were investigated. The emission band of freshly prepared Si-NPA located at ∼630 nm, and a blueshift at ∼425 nm as well as degradation in intensity after annealing at 600 deg. C for 1 h was observed, which might be explained by a quantum confinement effect model. BST ferroelectric material provided a static-electric field and induced the excited carriers in Si-NPA to migrate toward the opposite direction and recombine in an interfacial oxide layer. Therefore, BST enhanced blue emission of Si-NPA as well as passivated Si-NPA

14. Capacitive humidity sensing properties of carbon nanotubes grown on silicon nanoporous pillar array

JIANG WeiFen; XIAO ShunHua; ZHANG HuanYun; DONG YongFen; LI XinJian

2007-01-01

Multi-walled carbon nanotubes (CNTs) were grown on silicon nanoporous pillar array (Si-NPA) by thermal chemical vapor deposition method, and the structural and capacitive humidity sensing properties of CNT/Si-NPA were studied. It was found that with the relative humidity (RH) changing from 11% to 95%, a device response of ～480% was achieved at the frequency of 50000 Hz, and a linear device response curve could be obtained by adopting longitudinal logarithmic coordinate. The response/recovery times were measured to be ～20 s and ～10 s, respectively, which indicated a rather fast response/recovery rate. The adsorption-desorption dynamic cycle experiments demonstrated the high measurement reproducibility of CNT/Si-NPA sensors. These excellent performances were attributed to the unique surface structure, morphology and chemical inertness of CNT/Si-NPA.

15. Fabrication of an array of silicon microscales for the monitoring of chemical processes

We present the fabrication and demonstration of a two-dimensional array of scales micromachined in silicon. Each scale consists of a platform suspended by a spring. The mass present on the platform of each scale is measured from a distance by a camera, which is imaging the fringe pattern that arises from optical interference in an air gap under each scale. A diffractive lens at the bottom of the gap separates the fringe signal from unwanted reflections and directs the fringe signal towards the camera. When a mass deflects a scale platform downwards, the gap narrows at the scale centre and the fringe pattern gets tighter. Operation at temperatures as high as 700 °C was demonstrated, which makes the presented device useful for the monitoring of high-temperature chemical processes. (paper)

16. Spin-on-doping for output power improvement of silicon nanowire array based thermoelectric power generators

The output power of a silicon nanowire array (NWA)-bulk thermoelectric power generator (TEG) with Cu contacts is improved by spin-on-doping (SOD). The Si NWAs used in this work are fabricated via metal assisted chemical etching (MACE) of 0.01–0.02 Ω cm resistivity n- and p-type bulk, converting ∼4% of the bulk thickness into NWs. The MACE process is adapted to ensure crystalline NWs. Current-voltage and Seebeck voltage-temperature measurements show that while SOD mainly influences the contact resistance in bulk, it influences both contact resistance and power factor in NWA-bulk based TEGs. According to our experiments, using Si NWAs in combination with SOD increases the output power by an order of 3 under the same heating power due to an increased power factor, decreased thermal conductivity of the NWA and reduced Si-Cu contact resistance.

17. Surface-enhanced Raman scattering of patterned copper nanostructure electrolessly plated on arrayed nanoporous silicon pillars

Jiang Weifen; Shan Wenwen; Ling Hong; Wang Yusheng [Department of Mathematics and Information Science, North China Institute of Water Conservancy and Hydroelectric Power, Zhengzhou 450011 (China); Cao Yanxia [College of Materials Engineering, Zhengzhou University, Zhengzhou 450052, People' s Republic of China (China); Li Xinjian, E-mail: gingerwfj@yahoo.com.c [Department of Physics and Laboratory of Material Physics, Zhengzhou University, Zhengzhou 450052 (China)

2010-10-20

A new synthesized composite structure, a patterned copper/silicon nanoporous pillar array (Cu/Si-NPA) made by depositing Cu on Si-NPA using an immersion plating method, can be used as a surface-enhanced Raman scattering (SERS) substrate. Its surface component and morphology were analyzed by x-ray diffraction and field-emission scanning electron microscopy, respectively. It was found that the surface was Cu with two kinds of crystal structures: a continuous film composed of Cu nanocrystallites covering the Si-NPA, and a quasi-regular, interconnected network composed of loop-chains of Cu crystallites, with the size in the range of several tens of nanometer to 300 nm, surrounding the porous Si pillars. The composite structure is strongly SERS active using rhodamine 6G as probe molecules, which is mainly due to the patterned hierarchical Cu structure.

18. Application of silicon zig-zag wall arrays for anodes of Li-ion batteries

Li, G. V.; Rumyantsev, A. M.; Levitskii, V. S.; Beregulin, E. V.; Zhdanov, V. V.; Terukov, E. I.; Astrova, E. V.

2016-01-01

Cyclic tests of anodes based on zigzag wall arrays fabricated by the electrochemical etching and post-anodization treatment of silicon have been performed. Compared with anodes based on nanowires and planar thin films, these structures have several advantages. An ex situ analysis of the morphology and structural transformations in a material subjected to cyclic lithiation was conducted by electron microscopy and micro-Raman spectroscopy. The effect of geometrical parameters and a cycling mode on the degradation rate was studied. It is shown that a significant rise in the cycle life of the anode can be obtained by the restriction of the inserted amount of lithium. The anode, subjected to galvanostatic cycling at a rate С/2.8 at a limited charge capacity of 1000 mA · h g-1, demonstrates no degradation after 1200 cycles.

19. Photon counting pixel and array in amorphous silicon technology for large area digital medical imaging applications

2010-04-01

A single photon counting Voltage Controlled Oscillator (VCO) based pixel architecture in amorphous silicon (a-Si) technology is reported for large area digital medical imaging. The VCO converts X-ray generated input charge into an output oscillating frequency signal. Experimental results for an in-house fabricated VCO circuit in a-Si technology are presented and external readout circuits to extract the image information from the VCO's frequency output are discussed. These readout circuits can be optimized to reduce the fixed pattern noise and fringing effects in an imaging array containing many such VCO pixels. Noise estimations, stability simulations and measurements for the fabricated VCO are presented. The reported architecture is particularly promising for large area photon counting applications (e.g. low dose fluoroscopy, dental computed tomography (CT)) due to its very low input referred electronic noise, high sensitivity and ease of fabrication in low cost a-Si technology.

20. Periodic molybdenum disc array for light trapping in amorphous silicon layer

Wang, Jiwei; Yang, Kang; Chen, Haiyan; Deng, Changkai; Li, Dongdong; Chen, Xiaoyuan; Ren, Wei

2016-05-01

We demonstrate the light trapping effect in amorphous silicon (a-Si:H) layer by inserting a layer of periodic molybdenum disc array (MDA) between the a-Si:H layer and the quartz substrate, which forms a three-layer structure of Si/MDA/SiO2. The MDA layer was fabricated by a new cost-effective method based on nano-imprint technology. Further light absorption enhancement was realized through altering the topography of MDA by annealing it at 700°C. The mechanism of light absorption enhancement in a-Si:H interfaced with MDA was analyzed, and the electric field distribution and light absorption curve of the different layers in the Si/MDA structure under light illumination of different wavelengths were simulated by employing numerical finite difference time domain (FDTD) solutions.

1. Capacitive humidity sensing properties of carbon nanotubes grown on silicon nanoporous pillar array

2007-01-01

Multi-walled carbon nanotubes (CNTs) were grown on silicon nanoporous pillar array (Si-NPA) by thermal chemical vapor deposition method, and the structural and capacitive humidity sensing properties of CNT/Si-NPA were studied. It was found that with the relative humidity (RH) changing from 11% to 95%, a device re-sponse of ~480% was achieved at the frequency of 50000 Hz, and a linear device response curve could be obtained by adopting longitudinal logarithmic coordinate. The response/recovery times were measured to be ~20 s and ~10 s, respectively, which indicated a rather fast response/recovery rate. The adsorption-desorption dynamic cycle experiments demonstrated the high measurement reproducibility of CNT/Si-NPA sensors. These excellent performances were attributed to the unique surface structure, morphology and chemical inertness of CNT/Si-NPA.

2. Synthesis, characterization and application of electroless metal assisted silicon nanowire arrays

Sahoo, Sumanta Kumar; Marikani, Arumugam

2015-12-01

Vertically aligned silicon nanowire arrays (SiNWs) have been synthesized by electroless metal deposition process. The fabricated SiNWs have an average diameter of 75 nm and 3.5-4.0 μm length, as confirmed from scanning electron microscopy. A characteristic asymmetric peak broadening at 520 cm-1 from Raman spectroscopy was obtained for the SiNWs as compared to the bulk silicon crystal due to phonon confinement. The as-prepared SiNWs exhibit good electron field-emission properties with turn-on field of about 8.26 V μm-1 at a current density of 4.9 μA cm-2. The SiNWs was functionalized by coating with a thin gold metallic film for 60 s, and then used as bio-probe for the detection of bovine serum albumin (BSA) protein molecules. From the linear sweep voltammetry analysis, the Au coated SiNWs, exhibit linear response to the BSA analyte with increase in concentration. The minimum detection limit of the protein molecule was calculated of about 1.16 μM by the as-synthesized SiNWs probe.

3. An investigation into the fabrication and combustion performance of porous silicon nanoenergetic array chips

Wang, Shouxu; Shen, Ruiqi; Ye, Yinghua; Hu, Yan

2012-11-01

An investigation into the ignitions and combustions of porous silicon (PS) nanoenergetic material array chips (nECs) at different ignition voltages was performed. The PS nECs were fabricated by integrating PS nanoenergetic material (nEMs) matrices and Cr-microbridges (microigniters) on the surface of silicon substrates. The combustion of PS nECs was in ambient air. Its ignition and combustion were investigated by a testing system and an optical high-speed camera. Experimental results revealed that the combustion delay time of PS nEMs increased from 8.0 × 10-5 s to 1.1 × 10-4 s with the decrement of ignition voltages from 140 to 80 V. The scope of ignition energy ranged from 0.153 to 0.287 mJ by calculations. The reaction type was deflagration, from the analysis of the high-speed video of PS nECs. The comprehensive experimental results indicated that the combustion of PS nECs was ignited by the synergic effect of the heat and the plasma. The ignition experiments suggested that Cr-microbridges were reliable igniters to trigger the self-sustained combustion of PS nECs. The strong plume of flame emitted from the surface of PS nECs indicated that the PS nECs may be applied as micro/nano igniter chips and microthruster chips.

4. Cascaded active silicon microresonator array cross-connect circuits for WDM networks-on-chip

Poon, Andrew W.; Xu, Fang; Luo, Xianshu

2008-02-01

We propose a design of an optical switch on a silicon chip comprising a 5 × 5 array of cascaded waveguide-crossing-coupled microring resonator-based switches for photonic networks-on-chip applications. We adopt our recently demonstrated design of multimode-interference (MMI)-based wire waveguide crossings, instead of conventional plain waveguide crossings, for the merits of low loss and low crosstalk. The microring resonator is integrated with a lateral p-i-n diode for carrier-injection-based GHz-speed on-off switching. All 25 microring resonators are assumed to be identical within a relatively wide resonance line width. The optical circuit switch can employ a single wavelength channel or multiple wavelength channels that are spaced by the microring resonator free spectral range. We analyze the potential performance of the proposed photonic network in terms of (i) light path cross-connections loss budget, and (ii) DC on-off power consumption for establishing a light path. As a proof-of-concept, our initial experiments on cascaded passive silicon MMI-crossing-coupled microring resonators demonstrate 3.6-Gbit/s non-return-to-zero data transmissions at on- and off-resonance wavelengths.

5. Small-angle neutron scattering from oxygen precipitates in silicon annealed at low temperatures

SANS has been used to measure the diffusion coefficient of oxygen in silicon in the temperature range 500-550 deg C. The results show that the oxygen diffusion is enhanced by a factor of ∼10 or less above the normal diffusion line, D (cm2s-1) = 0.13exp(-2.53eV/kT). A diffusion line of D(cm2s-1) = 6x10-5exp(-1.86eV/kT) fits the new results together with previous SANS data. The results suggest that this is an effective diffusion coefficient between normal interstitial oxygen diffusion and possibly the diffusion of oxygen dimers. This work is consistent with more recent work by other authors. SANS has been used to study the spatial dependence of precipitates across the diameter of 8-inch crystals grown in the 1980's and 1990's. The results show that Czochralski silicon grown today no longer suffers from the inhomogeneous precipitate growth across the crystal diameter observed in the 1980's. Temperature dependent scattering observed at Q∼0.2A-1 was found to be due to inelastic processes using time-of-flight measurements on SANS. This inelastic scattering can cloud the elastic scattering from weakly scattering precipitates. The time-of-flight chopper on SANS was used to separate the elastic and inelastic events on samples annealed at 500 and 525 deg C. The results showed that the Guinier radius of the precipitates was of the order of ∼10A and suggested oxygen diffusion close to normal oxygen diffusion in silicon at 525 deg C. An improvement in background levels should enable better measurements on silicon annealed at lower temperatures using this new technique. An energy analysis of the inelastic scattering showed that these were due to Umklapp processes where neutrons were gaining energy from phonons, at Q∼0.4A-1 and energy transfer of ∼13meV. (author)

6. Compositionally-graded silicon-copper helical arrays as anodes for lithium-ion batteries

Polat, Deniz B.; Keles, Ozgul; Amine, Khalil

2016-02-01

Restrictions in silicon based anodes have been the subject of many researches for years. As an innovative approach, we have adopted ion assisted deposition technique to glancing angle deposition method and have used compositionally-graded structuring. A unique helical shaped gradient film has been produced in which the Cu/Si atomic ratio decreases from the bottom to the top of the coating. With such a unique film (high surface area) more spaces have been created promoting mechanical integrity and reaction between active materials (silicon) with lithium ions. The highly adherent film is formed as a result of ion assisted deposition process and the gradual change in Cu/Si atomic ratio diverts stress through the helices. To compare the performance of the SiCu electrode, a pure Si film is deposited in the same experimental condition. Galvanostatic test results show that although the film with pure Si helices fails after 30th cycles, the compositionally graded anode exhibits a capacity of 1228 mAh g-1 at the 100th cycles with 99.5% coulombic efficiencies when cycled at 100 mA g-1, and delivers 815 mAh g-1 when cycled with a rate of 400 mA g-1.

7. Simple, Fast, and Cost-Effective Fabrication of Wafer-Scale Nanohole Arrays on Silicon for Antireflection

Di Di

2014-01-01

Full Text Available A simple, fast, and cost-effective method was developed in this paper for the high-throughput fabrication of nanohole arrays on silicon (Si, which is utilized for antireflection. Wafer-scale polystyrene (PS monolayer colloidal crystal was developed as templates by spin-coating method. Metallic shadow mask was prepared by lifting off the oxygen etched PS beads from the deposited chromium film. Nanohole arrays were fabricated by Si dry etching. A series of nanohole arrays were fabricated with the similar diameter but with different depth. It is found that the maximum depth of the Si-hole was determined by the diameter of the Cr-mask. The antireflection ability of these Si-hole arrays was investigated. The results show that the reflection decreases with the depth of the Si-hole. The deepest Si-hole arrays show the best antireflection ability (reflection 600 nm, which was about 28 percent of the nonpatterned silicon wafer’s reflection. The proposed method has the potential for high-throughput fabrication of patterned Si wafer, and the low reflectivity allows the application of these wafers in crystalline silicon solar cells.

8. Influence of gallium ion beam acceleration voltage on the bend angle of amorphous silicon cantilevers

Kozeki, Takahiro; Phan, Hoang-Phuong; Viet Dao, Dzung; Inoue, Shozo; Namazu, Takahiro

2016-06-01

This paper describes a plastic reshaping technique for Si thin membranes by using focused ion beam (FIB) processing. FIB is used to locally pattern and implant Ga ions into the membranes. The combination of Ga ion doping and alkali wet etching enables us to fabricate nanometer-thick Ga-ion-doped amorphous Si membranes, which can be bent upward at arbitrary angle by controlling the FIB beam irradiation condition. The bending mechanism is discussed in the light of Ga ions implanted depth from the membrane surface. By using this technique, a micrometer-sized chute structure with several different angles is produced.

9. SHARC: Silicon Highly-segmented Array for Reactions and Coulex used in conjunction with the TIGRESS {gamma}-ray spectrometer

Diget, C A; Fox, S P; Adsley, P; Fulton, B R [Department of Physics, University of York, York, YO10 5DD (United Kingdom); Smith, A [School of Physics and Astronomy, The University of Manchester, Manchester, M13 9PL (United Kingdom); Williams, S; Ball, G C; Churchman, R M; Dech, J; Valentino, D Di; Djongolov, M [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3 (Canada); Porter-Peden, M [Department of Physics, Colorado School of Mines, Golden, CO 80401 (United States); Achouri, L [Laboratoire de Physique Corpusculaire, IN2P3-CNRS, ISMRA et Universite de Caen, F-14050 Caen (France); Al-Falou, H; Austin, R A E [Department of Astronomy and Physics, Saint Mary' s University, Halifax, NS, B3H 3C3 (Canada); Blackmon, J C [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803 (United States); Brown, S; Catford, W N [Department of Physics, University of Surrey, Guildford, GU2 5XH (United Kingdom); Chen, A A; Chen, J, E-mail: christian.diget@york.ac.uk [Department of Physics and Astronomy, McMaster University, Hamilton, ON, L8S 4M1 (Canada)

2011-02-01

The combination of {gamma}-ray spectroscopy and charged-particle spectroscopy is a powerful tool for the study of nuclear reactions with beams of nuclei far from stability. This paper presents a new silicon detector array, SHARC, the Silicon Highly-segmented Array for Reactions and Coulex. The array is used at the radioactive-ion-beam facility at TRIUMF (Canada), in conjunction with the TIGRESS {gamma}-ray spectrometer, and is built from custom Si-strip detectors utilising a fully digital readout. SHARC has more than 50% efficiency, approximately 1000-strip segmentation, angular resolutions of {Delta}{theta} {approx} 1.3 deg. and {Delta}{phi} {approx} 3.5 deg., 25-30 keV energy resolution, and thresholds of 200 keV for up to 25 MeV particles. SHARC is now complete, and the experimental program in nuclear astrophysics and nuclear structure has commenced.

10. Fabrication of silicon carbide nanowires/carbon nanotubes heterojunction arrays by high-flux Si ion implantation.

Liu, Huaping; Cheng, Guo-An; Liang, Changlin; Zheng, Ruiting

2008-06-18

An array of silicon carbide nanowire (SiCNW)-carbon nanotube (CNT) heterojunctions was fabricated by high-flux Si ion implantation into a multi-walled carbon nanotube (MWCNT) array with a metal vapor vacuum arc (MEVVA) ion source. Under Si irradiation, the top part of a CNT array was gradually transformed into an amorphous nanowire array with increasing Si dose while the bottom part still remained a CNT structure. X-ray photoelectron spectroscopy (XPS) analysis shows that the SiC compound was produced in the nanowire part even at the lower Si dose of 5 × 10(16) ions cm(-2), and the SiC amount increased with increasing the Si dose. Therefore, the fabrication of a SiCNW-CNT heterojunction array with the MEVVA technique has been successfully demonstrated. The corresponding formation mechanism of SiCNWs was proposed. PMID:21825818
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