Growth And Characterization Of GaN By Hydride Vapor Phase Epitaxy

In recent years considerable progress has been achieved in the design and fabrication of devices based on gallium nitride. However, unavailability of an appropriate substrate remains the main problem restraining further progress of devices based on GaN. One of the best solutions to this problem would have been the use of freestanding GaN substrates, which are grown by hydride vapor phase epitaxy (HVPE) due to its high growth rate. This dissertation focused on the growth and characterization of GaN by HVPE, including setting up the equipment of HVPE, simulating and designing the reactor of the equipment, studying the nucleation of GaN grown by HVPE, adopting some new ideas to grow high quality GaN and reduce the dislocation density in GaN film.The main results are summarized as follows:1. The growth system of HVPE was set up and the reactor of the equipment was simulated and designed by using the computational fluid dynamics (CFD) finite element software Fluent to grow high quality GaN.2. The natridation of sapphire substrate by NH3 at a high temperature was studied to provide the best nucleation condition for the growth of GaN film.3. It was found that that the HC1 growth interruption can change the polarity of the GaN film from N-polar into Ga-polar for the first time.4. The indium assistant growth was adopted for the first time to grow GaN film by HVPE, and the crystalline quality and surface morphology of the epi-layer were improved by using this method.5. The low-temperature A1N interlayer was used to grow GaN film by HVPE. It was shown that the annealed A1N interlayer helps to improve the crystalline quality of GaN film and relax the stress in the film.6. It was for the first time to use the anodic aluminum oxide (AAO) as a mask to grow GaN film by HVPE, which can improve the crystalline quality and optical property of GaN film.7. The metal tungsten interlayer was used to grow GaN film by HVPE for the first time.