Optical traveling-wave resonator architectures have shown promise for the realization of many compact photonic functionalities in different research disciplines. Realizing these resonator structures in high-index contrast silicon enables dense and large scale integration of large arrays of functionalized resonators in a CMOS-compatible technology platform. Based on these motivations, the main focus of this Ph.D. research has been on the device physics, modeling, implementations, and applications of planar ultra-high Q silicon traveling-wave microresonators in a silicon-on-insulator (SOI) platform. Microdisk, microring, and racetrack resonators are the three general traveling-wave resonator architectures of interests that I have investigated in this thesis, with greater emphasis on microdisks. I have developed efficient tools for the accurate modeling of these resonators. The coupling to these resonators has been through a nano-waveguide side coupled to them. For this purpose, I have developed a systematic method for engineering a waveguide-resonator structure for optimum coupling. I have addressed the development of nanofabrication techniques for these resonators with efficient interaction with a nano-waveguide and fully compatible with active electronic integration. The outcome of the theoretical design, fabrication, and characterization of these resonators is a world-record ultra-high Q (3×10[superscript 6]) with optimum waveguide-resonator interaction. I have investigated the scaling of these resonators toward the ultimate miniaturization and its impact on different physical properties of the resonators. As a result of these investigations, I have demonstrated miniaturized Si microdisk resonators with radii of ~ 1.5 micron and Q > 10⁵ with single-mode operation over the entire large free-spectral range. This is the highest Q (~ one order more than that in previously reported data) that has been obtained for a Si microdisk resonator with this size on a SiO₂ substrate. I have employed these resonators for more advanced functionalities such as large-scale integration of resonators for spectroscopic and filtering applications, as well as the design of flat-band coupled-resonator filter structures. By proposing a systematic method of design, I have shown ultra-compact coupled-resonator filters with bandwidths ranging from 0.4 to 1 nm. I have theoretically and experimentally investigated the performance of ultra-high Q resonators at high powers and in the presence of nonlinearities. At high powers, the presence of two-photon absorption, free-carrier generation, and thermo-optic properties of silicon results in a rich dynamic in the response of the resonator. In both theory and experiment, I have predicted and demonstrated self-sustained GHz oscillation on the amplitude of an ultra-high Q resonator pumped with a continuous-wave laser.

The development of new materials and processes for electronic devices has been driven by the integrated circuit (IC) industry since the dawn of the computer era. After several decades of '"Moore's Law"-type innovation, future miniaturization may be slowed down by materials and processing limitations. By way of comparison, the nascent field of flexible electronics is not driven by the smallest possible circuit dimension, but instead by cost and form-factor where features typical of 1970s CMOS (i.e., channel length - IO μm) will enable flexible electronic technologies such as RFID, e-paper, photovoltaics and health monitoring devices. In this thesis. cyclohexasilane is proposed and used as a key reagent in solution processing of poly-Si and Co-Si thin films with the former used as the active layer in thin film transistors (TFTs) and the latter as the gate metal in metal-oxide-semiconductor (MOS) capacitors. A work function of 4.356 eV was determined for the Co-Si thin films via capacitance-voltage (C-Y) characterization which differs slightly from that extracted from ultraviolet photoemission spectroscopy (UPS) data (i.e., 4.8 eV). Simulation showed the difference between the C-V and UPS-derived data may be attributed to the existence of 8.3 x 10 (exponent 10) cm-2 interface charge density in the oxide-semiconductor junction. Poly-Si TFTs prepared using Si6 H12-based inks maintained the following electrical attributes: field effect mobility of 0.1 cm2V-1s-1; threshold voltage of 66 V; and, an on/off ratio of 1630. A BSIM3 version 3 NFET model was modified through global parametric extraction procedure to match the transfer characteristics of the fabricated poly-Si TFT. It is anticipated that this model can be utilized for future design simulation for solution-processed poly-Si circuits.