Effect of GaNP Buffer Layer on AlGaN Epilayers Deposited on (0001) Sapphire Substrates by Metalorganic Chemical Vapor Deposition

Abstract

AlxGa1-xN (x ≤0.1) epilayers grown on (0001) sapphire substrates by low-pressure metalorganic chemical vapor deposition with low-temperature (LT)-GaNP buffer have been characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). It is found that the full width at half maximum (FWHM) values of the GaNP-buffer-based AlxGa1-xN (x ≤0.1) epilayers decrease are lower than that of the conventional GaN-buffer-based AlxGa1-xN (x ≤0.1) epilayers, but the difference becomes smaller as the Al composition increases. These results could be mainly attributed to a longer diffusion length with the GaNP buffer layer than with the GaN buffer layer.