Dependence of the HVPE GaN epilayer on GaN buffer layer for GaN direct growth on (001) GaAs substrate

Abstract

Cubic GaN was grown on (001) GaAs substrates by hydride vapor phase epitaxy (HVPE) with a buffer layer grown by low temperature HVPE. The crystalline structure of the GaN buffer layer is studied using reflection high-energy electron diffraction (RHEED). The GaN layers were grown at 800°C on the buffer layer with various growth temperatures and thicknesses. The optimum thickness of the buffer layer grown at 500°C to obtain a cubic GaN layer was found to be 60 nm in our case. When the buffer layer was grown at 525°C, however, the full width at half-maximum (FWHM) of the X-ray diffraction (XRD) pattern was 21.2 min, which is the narrowest ever reported, as far as we know. Furthermore, it was demonstrated that a single crystalline GaN buffer layer was necessary to obtain high-quality thick cubic GaN.