Improved GaN grown on Si(111) substrate using ammonia flow modulation on SiNx mask layer by MOCVD

In this paper, 1 μm n-GaN was grown by using varied and fixed ammonia flow (NH 3 ) on SiN x mask layer on Si(111) substrate using metal organic chemical vapor deposition (MOCVD). In-situ optical reflectivity traces of GaN growth show that the three- to two-dimensional process has been prolonged by using varied ammonia flow on SiN x mask layer method compared with that grown by fixing ammonia flow. Structural and optical properties were characterized by high-resolution X-ray diffraction and photoluminescence, and compared with the sample grown by fixing ammonia flow, GaN grown using the varied ammonia flow on SiN x mask layer showed better structure and optical quality. It was assumed that the low NH 3 flow in the initial growth stage considerably increased the GaN island density on the nano-porous SiN x layer by enhancing vertical growth. Lateral growth was significantly favored by high NH 3 flow in the subsequent step. As a result, the improved crystal and optical quality was achieved utilizing NH 3 flow modulation for GaN buffer growth on Si(111) substrate.