Growth and Characteristics of Silicon Nitride on Gallium Nitride by Plasma-Assisted Molecular Beam Epitaxy
In this dissertation, the gallium nitride and silicon nitride grown on c-plane sapphire substrate by plasma assisted molecular beam epitaxy (MBE) were studied. The photoluminescence (PL), scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS) were used to investigate the physical properties. The quality of GaN nano-rods can be improved by using low temperature GaN buffer layer and the control of N/Ga flux ratio and growth temperature. Under the highly N-rich condition, the GaN nano-rods formed a hexagonal shape at 760°C. The low temperature PL measurement showed that the full width at half maximum (FWHM) of the near band edge emission was 18 meV. On the other hand, the GaN formed thin film structure on GaN substrate which grown by Metal-organic Chemical Vapor Deposition (MOCVD). The low temperature PL spectra showed that the near band edge emission peak FWHM is 7 meV and without deep level emission, which can prove the quality of GaN has been greatly improved. The roughness of GaN film was 1.92 nm which observed by Atomic Force Microscope (AFM). XPS energy showed there was only Si-N bonding in the SiN and the growth rate was 0.82 nm/hour at least. The SiN can decrease the roughness of N-rich GaN. During the high electron mobility transistors (HEMTs) application, it will reduce the relaxation, cracking, and surface roughness of the top layer. That leads to devices with improved characteristics.
|Appears in Collections:||Thesis|