Cubic Dominant GaN Growth on (001) GaAs Substrates by Hydride Vapor Phase Epitaxy

GaN layers were grown on (001) GaAs substrates by hydride vapor phase epitaxy (HVPE) with buffer layers grown by HVPE under various growth conditions. The ratio of cubic to hexagonal components in the grown GaN layers was estimated from the ratio of the integrated X-ray diffraction intensities of the cubic (002) and hexagonal (1011) planes measured by ω scan. It was found that the cubic/hexagonal ratio greatly depended on the thermal cleaning prior to the buffer layer growth and growth conditions. A thick GaN layer whose cubic component was more than 85% was obtained with thermal cleaning at 600°C for 10 minutes, a ∼ 30 nm buffer layer grown at 500°C and a V/III ratio of 300 during growth at 800°C.