A NEW BUFFER LAYER FOR HIGH-QUALITY GAN GROWTH BY METALORGANIC VAPOR-PHASE EPITAXY

A new buffer layer to grow high-quality GaN films was proposed, The ne w buffer layer consisted of a thin (20-30 nm) InN layer deposited at l ow temperature (similar to 600 degrees C), GaN films were grown on (<1 1(2)over bar 0>)-oriented (A-face) sapphire substrates using a convent ional 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). Th e dislocation densities were measured from the TEM observation and wer e similar to 4x10(9) and similar to 6x10(8) 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 Ga N epilayers due to the low melting point of InN. GaN epilayers using t he InN buffer also showed good electrical properties. (C) 1998 America n Institute of Physics.