A new buffer layer for high quality GaN growth by metalorganic vapor phase epitaxy

Abstract

A new buffer layer to grow high-quality GaN films was proposed. The new buffer layer consisted of a thin (20–30 nm) InN layer deposited at low temperature (∼600 °C). GaN films were grown on (112̄0)-oriented (A-face) sapphire substrates using a conventional GaN buffer layer and an InN buffer layer by atmospheric pressure metalorganic vapor phase epitaxy. Dislocations in the GaN films were observed by cross-sectional transmission electron microscopy (TEM). The dislocation densities were measured from the TEM observation and were ∼4×109 and ∼6×108 cm−2 for epilayers with the GaN and the InN buffer, respectively. The low dislocation density by the InN buffer was attributed to relaxation of the stress in the GaN epilayers due to the low melting point of InN. GaN epilayers using the InN buffer also showed good electrical properties.