| dc.description.abstract | Gallium nitride (GaN) has advantages in wide bandgap and thermal stability, making it a crucial material in the semiconductor industry. Additionally, due to its large nonlinear coefficient, it is also beneficial for research in the field of nonlinear optics. Traditionally, GaN thin films are predominantly deposited using metal-organic chemical vapor deposition (MOCVD) or wafer bonding techniques. The advantage of MOCVD lies in its ability to deposit high-quality GaN thin films with lattice structures. However, its drawback is the need to consider lattice matching during deposition. Without good lattice matching, high-quality thin films cannot be achieved. Typically, GaN thin films are deposited on sapphire substrates, which are expensive, lack compatibility with complementary metal-oxide-semiconductor (CMOS) processes, and require high-temperature processing. On the other hand, wafer bonding allows integration onto CMOS-compatible substrates, but the initial deposition still requires lattice-matched substrates, involves more complex processing steps, and results in poorer surface quality of the thin films. To enable the deposition of high-quality thin films on a variety of substrates, this thesis employs high-power impulse magnetron sputtering (HiPIMS) for GaN thin film deposition. This deposition method utilizes high-energy ion bombardment to sputter the thin film onto the surface. Its advantages include the ability to deposit at room temperature without requiring lattice matching, allowing easy deposition on various substrates.
The thesis begins with an introduction to the fundamental theories of waveguides and micro-ring resonators, followed by simulations of the designed photomask to analyze the modes and field distributions, ensuring stable and efficient propagation within the waveguide structure. Simulations are then conducted to compare the effects of surface coating layers on field propagation. Finally, the feasibility of hybrid waveguides is verified through simulations, and the bending losses of hybrid waveguides made from different materials are compared, demonstrating the advantages of GaN hybrid waveguides. Leveraging the ability to deposit GaN films on various substrates, this thesis fabricates waveguides and micro-ring resonators using GaN thin films deposited on silicon, glass, and quartz substrates. By improving fabrication processes and optimizing photomask designs, efforts were made to reduce losses in both low-confinement and high-confinement waveguides while enhancing the quality factor of microring resonators. Ultimately, micro-ring resonators with resonances were successfully fabricated on quartz and glass substrates, and hybrid waveguides made with GaN achieved a micro-ring resonator quality factor of 104.
In conclusion, this thesis demonstrates the use of HiPIMS to deposit GaN on quartz and glass substrates to fabricate micro-ring resonators with resonances. Additionally, hybrid GaN waveguides were first developed to avoid losses associated with etching, providing a more versatile approach for GaN waveguide applications. | en_US |