Ammonothermal epitaxy of wurtzite GaN using an NH_4I mineralizer

摘要

Purely wurtzite phase needle crystals and epitaxial layers of GaN were grown by the ammonothermal method using an NH_4I mineralizer. The inclusion of zincblende phase GaN was effectively eliminated by increasing the growth temperature higher than 500 ℃. Accordingly, an approximately 20-μm-thick GaN epitaxial layer was achieved on the Ga-polar face of a c-plane GaN seed wafer at 520 ℃. Although the characteristic deep state emission band dominated the room temperature photoluminescence spectrum, the near-band-edge emission of GaN was observed for both the needle crystals and the epitaxial layers. These results encourage one to grow better quality GaN crystals at a high growth rate under high-temperature growth conditions.