Title of Invention: ELECTRIC FIELD-ASSISTED JUNCTIONS FOR SEQUENCING Abstract: Molecules may be analyzed (e.g., sequencing of nucleic acid molecules) by tunneling recognition at a tunneling junction. Embodiments of the present invention may allow detecting individual nucleotides and the sequencing of a nucleic acid molecule using a tunneling junction. By labeling a specific 5 nucleotide with a moiety, tunneling junctions may generate a signal with a suitable signal-to-noise ratio. An electric field may be applied to move the nucleic acid molecule and the moiety close to the tunneling junction so that a current may travel through the moiety. Because a single nucleotide can be detected with a signal with a suitable signal-to-noise ratio resulting from the tunneling current passing through 10 the moiety, embodiments of the present invention may allow for fast detection of nucleotides using a tunneling current. Detailed Description: BACKGROUND Technologies for analyzing single molecules (e.g. nucleic acids) include tunneling junction devices that have a sub-molecular sized gap between two conducting layers. Tunneling junctions use tunneling recognition. Tunneling recognition is based on placing a molecule or a portion of a molecule (e.g., a nucleotide of a nucleic acid) between conducting layers. When the molecule or the portion of the molecule contacts or is sufficiently close to both layers, the orbitals of the molecule or portion of the molecule will allow electrons to transfer from one layer to the other, creating a tunneling current. The tunneling current can be analyzed to identify the molecule or the portion of the molecule. To identify portions of the molecule, such as nucleotides, dimensions of the gap would normally have to be on the order of nanometers, including less than 2 nm, or even sub-nanometer. Creating a gap of this small size requires precise and expensive techniques. Reducing dimensions of the tunneling junction may also make contact of the molecule less frequent and for a shorter duration. Additionally, such a small gap size may cause shorts and may lead to a high background tunneling current. Therefore, improvements in the design and manufacturability of tunnel junctions used in chemical and biological detection and processes involving the devices are still needed. Design and manufacturability improvements should not come at the expense of accurate and precise analysis. These and other issues are addressed by the technology described in this document. BRIEF SUMMARY Embodiments of the present invention may allow for the analysis of molecules (e.g., sequencing of nucleic acid molecules) by tunneling recognition at a tunneling junction. The tunneling junction may be an electrical tunneling junction or a magnetic tunneling junction. Embodiments of the present invention may allow detecting individual nucleotides, and thus accurate sequencing of a nucleic acid using a tunneling junction may be achieved. By labeling a specific nucleotide with a moiety, tunneling junctions may generate a binary signal that is clear with a suitable signal-to-noise ratio. The tunneling recognition can use a tunneling current that is mostly through the moiety rather than mostly through the nucleotide or a portion of the molecule of interest. An electric field can be applied to move the molecule and the moiety closer to the tunneling junction. In this manner, the moiety is in a position close enough for current to pass through the moiety. The tunneling junction devices may focus on reading a single nucleotide at a time. Multiple and identical copies of a single-stranded nucleic acid molecule may be attached to the tunneling junction at one end of the molecules. The single-stranded nucleic acid molecules may be attached to an adhesion layer, which may be disposed on an electrode of the tunneling junction device. The single-stranded nucleic acid molecules may serve as template strands. Polymerases may be connected to the template strands and may be used to synthesize double-stranded DNA molecules using the template strands. A single type of nucleotide (e.g., A nucleotides) may be labeled with a moiety and introduced to the device. The nucleotide is incorporated into the DNA molecule if it is complementary to the template strand at a current position. The device may be washed of excess free nucleotides. An electric field may be applied using a field electrode to push the DNA molecule and the moiety toward the tunneling junction. If the nucleotide is added to the DNA molecule, then the moiety may cause a current signal in the tunneling junction. If the nucleotide is not added to the DNA molecule, then the current may be near zero. The moiety may then be removed. The next type of labeled nucleotide can be introduced to the device, and the process can be repeated. The current signal generated by the moiety may be a higher current than a background current through the nucleotide itself. Because a single nucleotide can be detected with a signal having a suitable signal-to-noise ratio resulting from the tunneling current passing through the moiety, embodiments of the present invention may allow for fast detection of nucleotides using a tunneling current. By detecting current through the moiety rather than the nucleotide itself, the dielectric in the tunneling junction may be thicker than the size of a single nucleotide. Hence, the tunneling junctions can be manufactured more easily, more cheaply, and more quickly. The tunneling junction devices may be manufactured with semiconductor processing techniques. The read time for detecting a nucleotide may approach or be equivalent to read times with flash drives. Incorporating a plurality of tunneling junctions into a single sequencing device may allow for multiplexing. Embodiments of the present invention may allow for a number of tunneling junctions similar to the number of tunneling junctions in a flash drive. In other words, billions of tunnel junctions could be incorporated in a device the size of a flash drive (an area on the order of a square centimeter). A highly multiplexed system may enable rapid and accurate sequencing. A better understanding of the nature and advantages of embodiments of the present invention may be gained with reference to the following detailed description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a graph of Random Telegraphic Noise (RTN) according to embodiments of the present invention. FIGS. 2A and 2B show diagrams of the tunneling current through a nucleotide with and without a moiety according to embodiments of the present invention. FIGS. 3A and 3B show the tunneling current response to a nucleotide with and without a moiety according to embodiments of the present invention. FIGS. 4A, 4B, and 4C show examples of a chemical compound that are modified nucleotides labeled with an organometallic moiety (OM) according to embodiments of the present invention. FIGS. 5A-5H illustrate configurations used in determining a nucleic acid sequence according to embodiments of the present invention. FIG. 6 illustrates steps of determining a nucleic acid sequence with an electrical tunneling junction according to embodiments of the present invention. FIG. 7 illustrates steps of determining a nucleic acid sequence with a magnetic tunneling junction according to embodiments of the present invention. FIGS. 8A-8C shows an example system used in determining a nucleic acid sequence according to embodiments of the present invention. FIG. 9 shows a configuration of electrodes of a tunneling junction according to embodiments of the present invention. FIG. 10 shows a configuration including a plurality of tunneling junctions according to embodiments of the present invention. FIGS. 11A and 11B show example systems with a magnetic tunneling junction according to embodiments of the present invention. FIG. 12 shows an example system with a tunneling junction with a tethered polymerase according to embodiments of the present invention. FIG. 13 shows an analysis system according to embodiments of the present invention. FIG. 14 shows a computer system according to embodiments of the present invention. FIG. 15 shows a computer system according to embodiments of the present invention. TERMS The term “contacting” may refer to bringing one object in proximity to another object such that electrons may tunnel from one object through the other object. At a subatomic level, two objects may never physically touch each other as repulsive forces from electron clouds in the objects may prevent the objects from coming into closer proximity. “Nucleic acid” may refer to deoxyribonucleotides or ribonucleotides and polymers thereof in either single- or double-stranded form. The term may encompass nucleic acids containing known nucleotide analogs or modified backbone residues or linkages, which are synthetic, naturally occurring, and non-naturally occurring, which have similar binding properties as the reference nucleic acid. Examples of such analogs may include, without limitation, phosphorothioates, phosphoramidates, methyl phosphonates, 2-O-methyl ribonucleotides, locked nucleic acids (LNAs), peptide nucleic acids (PNAs). Unless otherwise indicated, a particular nucleic acid sequence also implicitly encompasses conservatively modified variants thereof (e.g., degenerate codon substitutions) and complementary sequences, as well as the sequence explicitly indicated. Specifically, degenerate codon substitutions may be achieved by generating sequences in which the third position of one or more selected (or all) codons is substituted with mixed-base and/or deoxyinosine residues (Batzer et al., Nucleic Acid Res. 19:5081 (1991); Ohtsuka et al., J. Biol. Chem. 260:2605-2608 (1985); Rossolini et al., Mol. Cell. Probes 8:91-98 (1994)). The term nucleic acid is used interchangeably with gene, cDNA, mRNA, oligonucleotide, and polynucleotide. The term “nucleotide,” in addition to referring to the naturally occurring ribonucleotide or deoxyribonucleotide monomers, may be understood to refer to related structural variants thereof, including derivatives and analogs, that are functionally equivalent with respect to the particular context in which the nucleotide is being used (e.g., hybridization to a complementary base), unless the context clearly indicates otherwise. The term “oscillate” may refer to the motion of an object in a fluid as a result of Brownian motion or other forces. An object may oscillate without active intervention by a person or a machine. In some cases, an object may oscillate as a result of an applied electric field or a pressure-driven flow. The term “moiety” may include a functional group, as the technical term is used in chemistry. In addition, moiety may also refer to an atom or group of atoms bonded together that may form part of a larger compound. Moieties may include magnetic nanoparticles. Directional terms such as “above” or “on top of” for semiconductor processing layers and steps may use a reference frame where these terms designate a position farther away from a plane defined by a surface of the substrate. The “bottom” may be the underside of a substrate or toward the underside of the substrate. One of skill would understand that even if a substrate is processed upside-down, the “bottom” of a layer may still refer to a side of the layer closest to the underside or non-processed side of a substrate. The term “electrical characteristic” may be understood to refer to any property related to an electrical circuit. Electrical characteristic may refer to voltage, current, resistance, impedance, inductance, or capacitance, and time variations thereof (e.g., current frequency). DETAILED DESCRIPTION Tunneling recognition is a technique used to identify molecules or portions of molecules (e.g., a nucleic acid). A tunneling junction may include an electrical tunneling junction or a magnetic tunneling junction. An electrical tunneling junction may include two conductors sandwiching an insulating layer. When a molecule or a portion of the molecule contacts both conductors or is sufficiently close to both conductors, the current tunneling from one conductor to the other changes. The molecule or portion of the molecule may change the amplitude of the current by inducing direct conduction or trap-assisted tunneling. A magnetic tunneling junction may include two ferromagnetic materials sandwiching an insulating layer. When a magnetic nanoparticle is close to the ferromagnetic materials, the relative orientation of the magnetic domains changes and the current tunneling from one conductor to the other changes. The amount of tunneling current depends on the orientation of the magnetization (i.e., the spin) of the ferromagnetic materials. The current for ferromagnetic materials having the same spin (i.e., being parallel) is higher than two ferromagnetic materials having opposite spin (i.e., being antiparallel). With either junction, the tunneling current may vary depending on the identity of the molecule or portion of the molecule that contacts both conductors and how much the molecule oscillates between contacting and not contacting the conductors. If the current through only a single nucleotide of a nucleic acid is to be measured, the insulating layer would typically have to be less than the size of a nucleotide so that the nucleotide can contact both conductors across the insulating layer. However, even a thickness of 1 nm is about the size of three nucleotides, which can cause problems for detection of a single nucleotide. Even when the thickness of the insulating layer is on the order of 1 to 2 nm, manufacturing may still be difficult, and the background tunneling current through the thin insulating layer may be too large to detect a signal from the nucleotide or such a thin insulating layer may not prevent shorting. Increasing the thickness of the insulating layer may allow for easier manufacturing, but then a measurable tunneling current would need to pass through even more nucleotides. A signal passing through multiple nucleotides would involve more complicated signal analysis to identify the individual nucleotides. Embodiments of the present technology can reduce the noise in a current signal and do not require a thin insulating layer on the order of 1 to 2 nm. The tunneling junction devices may focus on reading a single nucleotide at a time. A single-stranded nucleic acid molecule (i.e., a template parent strand) may be attached or tethered to a tunneling junction. A double-stranded DNA molecule may be synthesized by polymerase connected to the template parent strand. Multiple template parent strands with multiple polymerases may be attached to the tunneling junction. Embodiments may include many tunneling junctions on the same device, allowing high multiplexing. In some embodiments, a set of nucleotides of a single type (e.g., A nucleotides) are labeled with a moiety and introduced to the device. These nucleotides may be added to a nascent strand when the nucleotides are of a type complementary to the template parent strand. The device may be washed of excess free nucleotides at this time or later in a cycle after introducing additional labeled nucleotides. An electric field may be applied to move the negatively charged nucleic acid molecule along with the moiety toward the tunneling junction (e.g., the insulating layer). The moiety may be brought close enough to allow current to tunnel from one conductor to the other conductor. In some embodiments, the moiety may contact both conductors to allow for a direct current path from one conductor to the other conductor. In embodiments where the moiety contacts both conductors to allow for a direct current path, the junction may be called a tunneling junction because the configuration of the junction may be similar or the same as a tunneling junction even though tunneling current is not the dominant current flowing through the junction. Multiple nucleic acid molecules attached to the tunneling junction may increase the probability of a current signal or may increase the strength of a current signal. If the nucleotide is added to the DNA molecule, then the moiety causes a current signal in the tunneling junction. If the nucleotide is not added to the DNA molecule, then the current may be near zero. The moiety may then be removed. A next type of labeled nucleotide can be introduced to the device, and the process may be repeated, thereby allowing a detection of whether a particular nucleotide is incorporated at each position. The current signal generated through the moiety may be higher than a background current through the nucleotide itself, thereby providing a signal with less noise. I. Using Random Telegraphic Noise (RTN) A tunneling current through the nucleotide or nucleotides themselves may not generate a high enough current signal with a suitable signal-to-noise ratio. The nucleotide may be in contact with the conductors for a short duration and the differences in tunneling currents between different nucleotides or sequences of nucleotides may be small. Accordingly, stronger and more easily detectable signals are desired. A. RTN To generate a current signal with a suitable signal-to-noise ratio, the current signal of embodiments of the present invention may mimic Random Telegraphic Noise (RTN), which previously referred to a problem with unwanted current signals in tunneling junctions. Without intending to be bound by a particular theory, one explanation for RTN is that impurities cause the unwanted current signals. The impurities may have trapped a charge and may sustain a higher current for a significant duration. The impurities may be imperfections in the oxide of the tunneling junction that act like charge traps. These impurities may include oxygen vacancies in the oxide, ions trapped in the metal oxide matrix, and substitute ions (e.g., dopants). After the impurity is no longer trapped the charge or the impurity left, the current drops. The devices in embodiments of the present invention intentionally recreate this RTN phenomenon with the tag of the labeled nucleotide. FIG. 1 shows a graph 100 of RTN in a plot of current versus time. The graph shows areas of higher current (e.g., area 102) and areas of lower, near-zero current (e.g., area 104). The areas of higher current may have a trapped charge, while the areas of lower current may not have a trapped charge. The analysis of whether a charge may be trapped may then depend on identifying where a higher current than the background current is present. B. Usage of Moiety To intentionally mimic RTN, a moiety that generates RTN can be attached to the molecule of interest. For example, if the molecule to be analyzed is a nucleic acid, a moiety can be attached to a nucleotide to be incorporated into a growing nucleic acid strand. FIGS. 2A and 2B show how a moiety may be used to generate a current signal. In FIG. 2A, the last nucleotide added to a nascent strand 202 by a polymerase 204 is connected to a moiety 208. Nascent strand 202 is being hybridized to a template parent strand 206 by polymerase 204. If moiety 208 is sufficiently close to a first conductor 210 and a second conductor 212, moiety 208 allows for an electron to tunnel from first conductor 210 to second conductor 212. Tunneling electrons may generate a current signal versus time similar to graph 220. The random nature of the current signal may be a result of capture and release of the trapped charge state and/or capacitive effects (i.e., charge and discharge). The capacitive effects may result from a trapped electron changing the charge distribution around the tunneling junction, which may change the height of the tunneling barrier. The amplitude of the current flowing through the junction may depend exponentially on the barrier height. Small changes in the barrier height caused by random charging and discharging of the trap state may result in large changes in the tunneling current, which are evident in FIG. 2A. In FIG. 2B, when no moiety is present, an electron cannot tunnel from first conductor 210 to second conductor 212. In FIG. 2B, the tunneling current should be near zero or near the background tunneling current, similar to graph 240. Hence, moiety 208 and therefore a nucleotide may be detected by measuring a tunneling current greater than zero or the background tunneling current. The moiety should be an entity that allows the tunneling current to pass through based on a certain potential applied. FIG. 3A shows the tunneling current response when no moiety is attached to a nucleotide. A polymerase 302 is close to tunneling junction 304. Polymerase 302 is hybridizing template parent strand 306. No moiety is present, and no charge is trapped. The tunneling junction is in an off-resonance trap state 308, which does not allow current to tunnel from one conductor to the other conductor. The result is a graph 310 of current versus time where the current is near zero and at a background level. FIG. 3B shows the tunneling current response when a moiety is attached to a nucleotide. A polymerase 312 is close to a tunneling junction 314. Polymerase 312 is hybridizing template parent strand 316. The nucleotide added has a moiety 318. Moiety 318 traps a charge at the electron transfer frequency. The tunneling junction is in an on-resonance trap state 320. A current can tunnel from one conductor through the moiety to the other conductor. The result is a graph 322 of current versus time where the current reaches a non-zero current and a current above a background level. II. Label Compound with Moiety The moiety used may be part of a label compound including more components than solely the moiety. The chemical compound used in methods and systems described herein may include a nucleotide, a cleavable linker, and a moiety. The nucleotide may include any of the four DNA nucleotides including adenine (A), thymine (T), guanine (G), and cytosine (C). The nucleotide may also include the four RNA nucleotides, including adenine, uracil (U), guanine, and cytosine. The label compound may be sufficiently long to allow contact of the moiety with the tunneling junction while an electrical field is applied to force the nucleic acid molecule at the moiety closer to the tunneling junction. For electrical tunneling junctions, the moiety may be selected from the group consisting of an organometallic group, a nanoparticle, a conjugated aromatic group, and a conductive organic molecule. Conductive organic molecules may have no bandgaps and may not be insulators or semiconductors. As examples, organometallic groups may include ferrocene, metal phthalocyanines (e.g., manganese phthalocyanine), ruthenium, osmium, and transition metal organometallic compounds. As examples, nanoparticles may include gold, silver, platinum, magnesium, or titanium nitride nanoparticles. Nanoparticles may include any particles having a characteristic size from 1 to 10 nm, including from 1 to 5 nm and from 5 to 10 nm. The characteristic size may be the diameter of the nanoparticle if the nanoparticle is a sphere. However, if the nanoparticle is not a sphere, the characteristic size may be the diameter of a sphere having the same volume as the non-spherical nanoparticle. In some instances, the characteristic size may be the minimum of the width, length, or height of a nanoparticle. Conjugated aromatic groups may include a compound with several benzene rings, including a compound with two to nine benzene rings, anthracene, phenanthrene, tetracene, chrysene, triphenylene, pyrene, pentacene, benzopyrene, corannulene, benzoperylene, coronene, ovalene, and benzofluorene. The conjugated aromatic group may include a compound with benzene rings arranged in linear structure. As examples, conductive organic molecules may include short polymers including poly-pyrrole and poly-aniline. The moiety, as mentioned above, may allow for a tunneling current by holding a charge in an on-resonance trap state. In some embodiments, the same moiety may be attached to the four nucleotides. In other embodiments, different moieties may be used for different nucleotides, with each moiety generating a different tunneling current for an applied voltage. The moiety may comprise multiple groups, such as multiple organometallic groups. The moiety may not be highly negatively or positively charged. A charged moiety may result in unwanted repulsion or attraction toward a DNA molecule. For magnetic tunneling junctions, the moiety may be selected from the group consisting of a ferromagnetic or superparamagnetic material. Materials may include a magnetic nanoparticle (e.g., FePt, FeCuPt, Fe2O3). A nanoparticle may have a diameter or characteristic size less than 1 μm, 500 nm, 100 nm, or 10 nm. The chemical compound may have a structure represented by N-X-S-M, where N is the nucleotide, X is the cleavable linker, S is a spacer, and M is the moiety. The nucleotide may be bonded directed to the cleavable linker. The cleavable linker may allow the label compound to be cleaved from the incorporated nucleotide after detection. Cleavable linkers are known in the art and have been described e.g., in U.S. Pat. Nos. 7,057,026, 7,414,116 and continuations and improvements thereof. In some embodiments, the label is attached to the 5-position in pyrimidines or the 7-position in purines via a linker comprising an allyl or azido group. In other embodiments, the linker comprises a disulfide, indole or a Sieber group. The linker may further contain one or more substituents selected from alkyl (C1-6) or alkoxy (C1-6), nitro, cyano, fluoro groups or groups with similar properties. Briefly, the linker can be cleaved by water-soluble phosphines or phosphine-based transition metal-containing catalysts. Other linkers and linker cleavage mechanisms are known in the art. For example, linkers comprising trityl, p-alkoxybenzyl esters and p-alkoxybenzyl amides and tert-butyloxycarbonyl (Boc) groups and the acetal system can be cleaved under acidic conditions by a proton-releasing cleavage agent. A thioacetal or other sulfur-containing linker can be cleaved using a thiophilic metals, such as nickel, silver or mercury. Cleavage protecting groups can also be considered for the preparation of suitable linker molecules. Ester- and disulfide containing linkers can be cleaved under reductive conditions. Linkers containing triisopropyl silane (TIPS) or t-butyldimethyl silane (TBDMS) can be cleaved in the presence of F ions. Photocleavable linkers cleaved by a wavelength that does not affect other components of the reaction mixture include linkers comprising O-nitrobenzyl groups. Linkers comprising benzyloxycarbonyl groups can be cleaved by Pd-based catalysts. As examples, the cleavable linker X may be cleavable by a metal catalyst (e.g., an allyl group), an enzyme (e.g., protease cleavage site, Tobacco Etch Virus [TEV] cleavage site), light (e.g., nitrobenzene), reduction (e.g., disulfide), an acid (e.g., acetals, methoxymethyl, or protected acetals [e.g., O—CH2—N3 or —O—CH(N3)—]), a base (e.g., succinate, acetyl), oxidation (e.g., vicinal diols), or a phosphatase (e.g., phosphate). The cleavable linker may include —O—NH2, which may be cleaved with nitrite. As examples, the spacer may be a polyethylene glycol (PEG), alkyl or aryl spacer, peptide, cationic spacer (e.g., spermine), nucleic acid, carbohydrate, or combinations thereof. FIG. 4A shows an example of a chemical compound. In FIG. 4A, the linker-spacer-moiety is attached to the 3′ OH group of the deoxyribose sugar. The nucleotide is linked to X, the cleavable linker, a spacer, and then a organometallic (OM) moiety. Blocking the 3′-OH group may automatically terminate the polymerase reaction. However, a 3′-OH with a bulky compound may not be readily accepted by polymerases. FIG. 4B shows an example of another chemical compound. The linker-spacer-moiety is attached to the base of the nucleotide. Modifying the base is usually well accepted by polymerases. However, because the 3′-OH group is not blocked, the compound in FIG. 4B may lead to less than 100% termination. FIG. 4C shows yet another example of a chemical compound. Both the base and the 3′ OH group can be bonded to a cleavable linker X. The linker X bonded to the base may be the same linker as X bonded to the 3′ OH group. However, in some embodiments, the two linkers may be different compounds. The compound in FIG. 4C may incorporate the advantages of both the compound in FIG. 4A and the compound in FIG. 4B. Adding a small cleavable terminator group at the 3′-OH group may ensure a stop after incorporation. Attaching a large X-S-M compound onto the base may not disturb the polymerase too much. However, FIG. 4C may need to be cleaved at two sites instead of just one site. The linker-spacer-moiety may act as a lightning terminator (Stupi, B. P. et al., “Stereochemistry of benzylic carbon substitution coupled with ring modification of 2-nitrobenzyl groups as key determinants for fast-cleaving reversible terminators,” Angew. Chem. Int. Ed., 51, 1724-1727 (2012), frios@example.net/doi/epdf/10.1002/anie.201106516) or as a virtual terminator (Bowers, J. et al., “Virtual terminator nucleotides for next-generation DNA sequencing,” Nature Methods, 6, 593-595 (2009), frios@example.net/articles/nmeth.1354.pdf and associated supplemental information frios@example.net/original/nature-assets/nmeth/journal/v6/n8/extref/nmeth.1354-S1.pdf). The chemical compound may also include a terminator. The terminator may stop a polymerization process. For example, with a polymerase, the terminator may stop the polymerase from adding nucleotides until the terminator is removed. The linker, spacer, moiety, or the combination thereof may act as a terminator. The label compounds in FIGS. 4A, 4B, and 4C may each include a terminator. If the molecule to be analyzed is not a nucleic acid, the chemical compound may be adapted accordingly. The label compound may be attached to a single unit of a biological polymer. For example, if the chemical compound to be analyzed is a protein, the label compound may be attached to an amino acid instead of a nucleotide. III. Methods of Analyzing Molecule The sequencing device may include two conductors separated by an insulating layer. The configuration of conductors and the insulating layer may be the same as a parallel plate capacitor or a tunneling junction. The tunneling junction may be an electrical tunneling junction or a magnetic tunneling junction. These configurations of conductors may be used to determine a sequence of a nucleic acid. Methods may include connecting a polymerase to a template parent strand attached to the sequencing device. The sequencing device may include a first conductor and a second conductor separated by an insulating layer. Methods may include adding a set of nucleotides to the sequencing device. Each nucleotide of the set of nucleotides may be attached to a label compound. The label compound may include a moiety. Methods may further include elongating a nascent strand using the polymerase connected to the template parent strand to be sequenced. Elongating may include the polymerase incorporating a first nucleotide of the set of nucleotides into the nascent strand via hybridization to the template parent strand. Methods may include applying an electric potential to move the template parent strand and a first moiety of a first label compound attached to the first nucleotide closer to the insulating layer while the template parent strand is attached to the sequencing device. Methods may then include measuring a value of an electrical or magnetic characteristic through the first conductor, the first moiety, and the second conductor while applying the electric potential. Methods may include detecting the first nucleotide as being hybridized to the template parent strand using the value of the electrical or magnetic characteristic. Methods for electrical tunneling junctions and magnetic tunneling junctions are described below. A. Electrical Field-Assisted Junction Configurations FIGS. 5A-5G illustrate configurations used in determining a nucleic acid sequence. The sequencing device in FIGS. 5A-5G is provided to facilitate explanation, but sequencing devices and methods are not limited to the depictions in these figures. FIG. 5A shows a tunneling junction 500. Tunneling junction 500 includes a first tunneling electrode 502 and a second tunneling electrode 504. First tunneling electrode 502 and second tunneling electrode 504 are separated by an insulating material 506 that forms an insulating layer 508 between the two tunneling electrodes. An adhesion layer 510 may be disposed on top of first tunneling electrode 502, second tunneling electrode 504, and insulating layer 508. Adhesion layer 510 may be a surface functionalization layer and may include silicon dioxide or alumina. The surface functionalization layer includes modifying a surface to include functional groups that allow for covalent bonding. First tunneling electrode 502 and second tunneling electrode 504 may be a metal material that does not allow for strong adhesion of nucleic acid molecules, and insulating layer 508 may be too thin for attaching nucleic acid molecules. Adhesion layer 510 allows for attachment of a nucleic acid molecule. The nucleic acid may attach to adhesion layer 510 by bonding with a compound that covalently bonds to silicon dioxide or alumina through an oxygen atom. The junction may be operational without adhesion layer 510. A fluidic space 512 may separate adhesion layer 510 from a first field electrode 514. Fluidic space 512 may be filled with a liquid when tunneling junction 500 is being used for sequencing. In some embodiments, first field electrode 514 may not contact the liquid. For example, fluidic space 512 may be enclosed by a housing, which may be glass or plastic. First field electrode 514 may be outside the housing, but the electric field may still affect the space within the housing. Insulating material 506 may separate the tunneling electrodes from a second field electrode 516. FIG. 5B shows tunneling junction 500 after identical copies of single-stranded DNA 520 are obtained. The identical copies of single-stranded DNA 520 may be obtained by bridge amplification. Bridge amplification may include adding adapters to both ends of DNA fragments. The adapters may include primers. These fragments may then be bound to a surface by an adapter. Both ends of a DNA fragment may be attached to the surface by the adapters forming a bridge-like structure. A polymerase synthesis the reverse strand of the DNA fragment to form a double-stranded DNA. The double-stranded DNA is then denatured to leave two strands of single-stranded DNA. The surface may be covered with a plurality of adapters. The adapters may be randomly distributed on the surface or arranged in a grid. There may be two types of adapters, with one type of adapter being complementary to an adapter at one end of the DNA fragment and a second type of adapter being complementary to an adapter at a second end of the DNA fragment. The two strands of single-stranded DNA may hybridize with the complementary adapter, forming two bridge-like structures. Each single-stranded DNA is hybridized to form double-stranded DNA. The double-stranded DNA is denatured again. The process may be repeated. As a result, the surface may be left with many single-stranded DNA densely attached to the surface. The identical copies may also be obtained by rolling circle amplification or other suitable amplification techniques. One type of adapter may be cleavable, and these adapters may be cleaved so that all the single-strands of DNA are attached to the surface at the same end (3′ or 5′). Other techniques may be used to ensure all strands are in the same direction. Single-stranded DNA 520 may be attached to adhesion layer 510. Single-stranded DNA 520 may attach to adhesion layer 510 more easily or more strongly than first tunneling electrode 502, second tunneling electrode 504, or insulating layer 508. FIG. 5C shows tunneling junction 500 after adding primers. Primer 530 is added to single-stranded DNA 520 to form a section of double-stranded DNA. Each single-stranded DNA shown in FIG. 5C has a primer added to it. FIG. 5D shows tunneling junction 500 after adding polymerase. Polymerase 540 is connected to single-stranded DNA 520 and primer 530. Each single-stranded DNA shown in FIG. 5D has a polymerase connected to it. FIG. 5E shows tunneling junction 500 after a set of nucleotides is added. Nucleotides with label compounds are incorporated by the polymerase and hybridized to the single-stranded DNA. The nucleotides added may all be the same type of nucleotide. The label compounds may be any label compound described herein. As an example in FIG. 5E, polymerase 540 is incorporating a nucleotide with a label compound with moiety 550. The moieties are at a distance that do not significantly affect a tunneling current from first tunneling electrode 502 to second tunneling electrode 504. FIG. 5F shows detecting a nucleotide with tunneling junction 500. A negative potential is applied to first field electrode 514. A positive potential is applied to second field electrode 516. Because DNA is negatively charged, DNA moves away from first field electrode 514 and toward second field electrode 516. As a result, the DNA moves toward first tunneling electrode 502, insulating layer 508, and second tunneling electrode 504. Consequently, nucleotides with label compounds with moieties also move toward first tunneling electrode 502, insulating layer 508, and second tunneling electrode 504. For example, moiety 550 may move closer to first tunneling electrode 502, insulating layer 508, and second tunneling electrode 504. Moiety 550 may be at a distance where the tunneling current from first tunneling electrode 502 to second tunneling electrode 504 is affected by the presence of moiety 550 and a difference in tunneling current may be measured. Moieties near 550 connected to adjacent or nearby DNA may also affect the tunneling current similarly. Although a negative voltage is described for first field electrode 514 and a positive voltage for second field electrode 516, one electrode need not be negative and the other electrode need not be positive. The electric field is based on the relative voltages between the two electrodes. For example, first field electrode 514 may have a positive voltage, and second field electrode 516 may have a positive voltage of an even greater magnitude. The effect on tunneling current may result in the random telegraphic noise (RTN) described herein. In other words, the tunneling current may be higher when negative potential is applied to first field electrode 514 than when no negative potential is applied or when no nucleotide with a label compound including a moiety is incorporated. In some embodiments, a current may not undergo quantum tunneling but instead may travel from first tunneling electrode 502 to moiety 550 to second tunneling electrode 504. Adhesion layer 510 is shown in FIG. 5F separating moiety 550 from first tunneling electrode 502, insulating layer 508, and second tunneling electrode 504. In some cases, additional polymerases may be added to replace some polymerases that may have detached from the DNA. FIG. 5F shows second field electrode 516 with a positive potential applied. However, second field electrode 516 need not be at a positive potential but instead should be positive with respect to first field electrode 514. Likewise, first field electrode 514 need not be at a negative potential but should be negative with respect to second field electrode 516. Additionally, both field electrodes may not be present as electrodes separate from the tunneling electrodes. For example, second field electrode 516 may not be present while first field electrode 514 is present. A negative potential is applied to first field electrode 514 relative to the potentials applied to first tunneling electrode 502 and/or second tunneling electrode 504. The tunneling electrodes may then act as the second field electrode. Similarly, second field electrode 516 may be present without first field electrode 514. A positive potential may be applied to second field electrode 516 relative to the fluid surrounding the DNA. The positive potential may attract DNA toward the tunneling junction. Having adhesion layer 510 in this illustrated position would reduce the effect of moiety 550 on the tunneling current for a given distance. However, FIG. 5F is a two-dimensional rendering of tunneling junction 500 and does not exclude a configuration where adhesion layer 510 may not cover parts of first tunneling electrode 502, insulating layer 508, and/or second tunneling electrode 504. FIG. 5G shows different possible top views of adhesion layer 510 where adhesion layer 510 may not cover parts of the underlying layers. In the top portion of FIG. 5G, adhesion layer 510 defines a circle that exposes a circular portion of insulating layer 508. The middle portion of FIG. 5G shows that adhesion layer 510 defines a rectangle, where a rectangular portion of insulating layer 508 is exposed. The bottom portion of FIG. 5G shows a configuration similar to the middle portion of FIG. 5G, except that portions of first tunneling electrode 502 and second tunneling electrode 504 are also exposed. Exposing the portions of first tunneling electrode 502 and second tunneling electrode 504 may allow for the electrodes to make direct contact with the moiety in order to obtain a signal. FIG. 5H shows tunneling junction 500 after removing label compounds from the nucleotide. The label compound includes a linker 560 and a moiety 562. The label compounds may be cleaved by photochemistry, chemistry, enzymatic reaction, or any technique described herein. The label compound may then be removed by flushing with a fluidic flow. If polymerases were removed, polymerases can be added again. B. Example Method with Electrical Tunneling Junction. FIG. 6 shows a method 600 of determining a sequence of a nucleic acid using a sequencing device according to embodiments of the present technology. The sequencing device may include an electrical tunneling junction, a first power supply, and a meter device. The tunneling junction includes a first conductor and a second conductor separated by an insulating layer. The first conductor and the second conductors may therefore be electrodes of the tunneling junction. The first power supply may be in electrical communication with the electrodes of the tunneling junction. A second power supply may be in electrical communication with a field electrode, which is separate from the electrodes of the tunneling junction. Method 600 may include attaching a template parent strand to the sequencing device. Method 600 may further include attaching a primer to the template parent strand before block 602. In some embodiments, the template parent strand is one of a set of template parent strands. In these embodiments, a set of primers may be attached to the set of template parent strands. The device may resemble the illustration in FIG. 5C. In some embodiments, a second set of primers may be attached to the sequencing device, with the second set of primers being complementary to a first set of primers attached to the set of template parent strands. The template parent strands may then be attached to the sequencing device as a result of the first set of primers being attached to the second set of primers. At block 602, a polymerase is connected to the template parent strand attached to the sequencing device. The template parent strand may be attached to an adhesion layer with primers attached to the adhesion layer, as explained above. The adhesion layer may contact the first conductor. In some embodiments, the adhesion layer may contact the second conductor and/or the insulating layer. The adhesion layer may include silicon dioxide, alumina, silicon, diamond-like carbon, silicon nitride, gold, or any suitable material that improves covalent bonding of the template parent strand to the tunneling junction. In embodiments, the template parent strand may be one template parent strand of a set of template parent strands. The polymerase may be one polymerase of a set of polymerases. Methods may include connecting the set of polymerases to the set of template parent strands. Each polymerase of the set of polymerases may be connected to one and only one template parent strand of the set of template parent strands. Each template parent strand of the set of template parent strands may be connected to one and only one polymerase of the set of polymerases. After connecting the polymerase at block 602, the configuration may resemble the illustration of FIG. 5D. The set of template parent strands may have been formed by amplifying a smaller set of template parent strands attached to the sequencing device. In some embodiments, the forward strands may be removed. In other embodiments the reverse strands may be removed. The remaining template parent strands may all be in the same direction and may be identical. Accordingly, the set of template parent strands can be formed by bridge amplification. At block 604, a set of nucleotides is added to the sequencing device. Each nucleotide of the set of nucleotides is attached to a label compound including a moiety. The set of nucleotides may be added to the sequencing device by including the set of nucleotides in a liquid that contacts the sequencing device. The liquid may be an ionic liquid. The moiety may be selected from the group consisting of an organometallic compound, a nanoparticle, and a conjugated aromatic, or may be any moiety described herein. Each nucleotide of the set of nucleotides may be attached to a respective label compound including a respective moiety. In some embodiments, each nucleotide of the set of nucleotides may be the same type of nucleotide. For example, each nucleotide of the set of nucleotides may be G nucleotides. Each moiety of each label compound may be the same type of moiety. In other embodiments, the set of nucleotides may include two, three, or four types of nucleotides. In these embodiments, each nucleotide may be attached to a different type of moiety. The liquid with the set of nucleotides may be stored in a reservoir and introduced by an injection system to the tunneling junction. At block 606, a nascent strand is elongated using the polymerase. The polymerase is connected to the template parent strand to be sequenced. Elongating includes the polymerase incorporating a first nucleotide of the set of nucleotides into the nascent strand. A nascent strand may be a single-stranded nucleic acid molecule. Elongating the strand may include incorporating a first nucleotide of the set of nucleotides into the nascent strand via hybridization to the template parent strand. Together, the nascent strand and the template parent strand may form a portion of a double-stranded nucleic acid molecule. The label compound may include a terminator configured to prevent further elongation of the nascent strand. A problem with conventional tunneling junctions in sequencing may be that a molecule to be analyzed may flow past the junction too quickly, making contact with the electrode for a short duration. The current signal may then be too short and difficult to characterize. In addition, even if only one type of nucleotide is added in block 604, a particular sequence in the template parent strand may include the same type of nucleotide multiple times and consecutively. The nucleic acid molecule may then add multiple nucleotides of the same type from a single introduction. As a result, the device may generate only one signal for one nucleotide when multiple nucleotides have been added. The terminator may stop polymerase action until the terminator is removed. In this manner, only one nucleotide may be added at a time, allowing enough time for a current signal to be measured. The set of nucleotides except the first nucleotide may be removed from contacting the tunneling junction. Removing the nucleotides may include rinsing the tunneling junction with water. The liquid used to rinse the tunneling junction may be water or an ionic liquid without a nucleotide. This rinse liquid may be stored in a reservoir and introduced to the tunneling junction with an injection system. Removing the set of nucleotides may occur before measuring a value of the electrical characteristic. In other embodiments, the set of nucleotides may not be removed before measuring the value of the electrical characteristic. After block 606, the device may resemble the configuration in FIG. 5E. At block 608, an electric potential is applied to move the template parent strand and a first moiety of a first label compound attached to the first nucleotide closer to the insulating layer while the template parent strand is attached to the sequencing device. The electric potential may be applied by the second power supply mentioned above to the field electrode. In some embodiments, applying the electrical potential may move the first moiety of the first label compound to contact the first conductor and the second conductor. In embodiments, the first moiety may be moved to a distance where a current can tunnel from the first conductor through the first moiety to the second conductor when the voltage is applied across the first conductor and the second conductor. Applying the electric field may include applying a negative voltage to an electrode. The negative voltage may be in a range from −1 V to 0 V, including −1 V to −0.75V, −0.75 V to −0.50 V, −0.50 V to −0.25 V, −0.25 V to −0 V. Applying the electrical field may include applying a positive voltage to another electrode. The positive voltage may be from 0 V to +1 V, including for example, 0 V to 0.25 V, 0.25 V to 0.50 V, 0.50 V to 0.75 V, or 0.75 V to 1.0 V. The voltage difference between the two electrode may be any voltage difference greater than 0 V and less than 2 V, including from 0.25 V to 0.50 V, from 0.50 V to 0.75 V, or 0.75 V to 1.0 V, from 1.0 V to 1.25 V, from 1.25 V to 1.50 V, from 1.50 V to 1.75 V, or from 1.75 V to 2.00 V. The electrode may be disposed such that the nascent strand is between the electrode and the insulating layer. The template parent strand, the polymerase, and/or the first label compound may be between the electrode and the insulating layer. In some embodiments, strands that did not incorporate a nucleotide may be capped. Capping of strands allows for avoiding analyzing strands that have not incorporated any nucleotide after a cycle of nucleotides. For example, strands may not incorporate any of A, T, G, and C nucleotides after each one is introduced. If these strands then incorporate a nucleotide after the cycle, the strands would be out-of-phase with other strands that did incorporate a nucleotide within the last cycle. To reduce these out-of-phase readings, the strands may be capped so that they do not incorporate additional nucleotides. At block 610, a voltage is applied across the first conductor and the second conductor. The voltage may be any voltage suitable to generate a current through an entity that contacts the tunneling junction. The current may be a tunneling current. The voltage may be applied after removing the set of nucleotides except for the first nucleotide (e.g., after rinsing). In some embodiments, the voltage may be applied for a longer duration, including before the rinse, during elongation (e.g.,
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