Selective area growth of GaN using gas source molecular beam epitaxy

Ammonia cracking efficiencies on various surfaces were examined. The following is an ordering of surfaces according to their ammonia cracking efficiencies: GaN (highest), Si3N4, SiO2 (lowest). Selective area growth of GaN was performed over SiO2 masks deposited on GaN previously grown on sapphire substrates using ammonia-based molecular beam epitaxy. GaN growth on patterned SiO2/GaN is very selective at a growth temperature of 800°C. Good quality growth occurs in the window region with no deposits on the mask surface when growth is performed at 800°C, whereas some deposits on the SiO2 masks accumulate when growth is performed at 700°C. The ratio of lateral growth rate to vertical growth rate is ≤1.