Comparison of Hydride Vapor Phase Epitaxy of GaN Layers on Cubic GaN/(100)GaAs and Hexagonal GaN/(111)GaAs Substrates

Abstract

GaN layers were homoepitaxially grown by hydride vapor phase epitaxy (HVPE) on cubic GaN/(100)GaAs and hexagonal GaN/(111)GaAs substrates, and the growth conditions and crystalline qualities were compared between both cases. HVPE GaN layers were epitaxially grown on hexagonal GaN/(111)GaAs substrates when the substrate temperature was below 700°C, whereas on cubic GaN/(100)GaAs substrates, they were epitaxially grown only at substrate temperatures above 800°C. Two-step growth was necessary for higher-quality hexagonal GaN epilayers to be grown at 900°C. The growth rate of HVPE GaN epilayers on hexagonal GaN/(111)GaAs substrates was about 2.5 times higher than that on cubic GaN/(100)GaAs substrates at the same HVPE growth conditions. Cathodoluminescence spectra were measured for HVPE epilayers grown on both substrates.