Title: In-situ Optical Characterization of Noble Metal Thin Film Deposition and Development of a High-performance Plasmonic Sensor,
Abstract: The present work addressed in this thesis introduces, for the first time, the
use of tilted fiber Bragg grating (TFBG) sensors for accurate, real-time, and
in-situ characterization of CVD and ALD processes for noble metals, but with a
particular focus on gold due to its desirable optical and plasmonic properties.
Through the use of orthogonally-polarized transverse electric (TE) and
transverse magnetic (TM) resonance modes imposed by a boundary condition at the
cladding-metal interface of the optical fiber, polarization-dependent
resonances excited by the TFBG are easily decoupled. It was found that for
ultrathin thicknesses of gold films from CVD (~6-65 nm), the anisotropic
property of these films made it non-trivial to characterize their effective
optical properties such as the real component of the permittivity.
Nevertheless, the TFBG introduces a new sensing platform to the ALD and CVD
community for extremely sensitive in-situ process monitoring. We later also
demonstrate thin film growth at low (<10 cycle) numbers for the well-known
Al2O3 thermal ALD process, as well as the plasma-enhanced gold ALD process.
Finally, the use of ALD-grown gold coatings has been employed for the
development of a plasmonic TFBG-based sensor with ultimate refractometric
sensitivity (~550 nm/RIU).