Growth of thick and pure cubic GaN on (0 0 1) GaAs by halide VPE

Abstract

To obtain a thick and pure cubic GaN layer, a hybrid growth of the halide vapor phase epitaxy (HVPE) and the metal organic MBE (MOMBE) was performed. An about 20 nm thick GaN buffer layer was grown on (0 0 1) GaAs by MOMBE using tertiary butyl hydrazine in a MBE chamber. Thick GaN layers were grown on it by a conventional HVPE system using H 2 as a carrier gas. When the thickness was less than 2 μm, the hexagonal component in the grown layer was less than 1% for a V/III ratio of 200, but it increased exponentially with an increase of the growth time and it became about 10% at 5 μm (2 h growth) and about 40% at 10 μm (3 h growth). These thicknesses are about three times larger than those generally obtained by GSMBE or MOVPE with the same hexagonal content. The grown surface became rough with an increase of thickness and therefore of hexagonal content. Photoluminescence was very poor even for a pure cubic GaN probably due to autodoping by arsenic.