Growth of AlGaN and GaN films on (1120) Al2O3 substrates and the influence of V/III ratio on the properties of GaN films

Abstract

AlGaN and GaN films were grown on (11 (2) over bar0) Al2O3 Substrates at elevated temperatures by alternate supply of trimethylgallium (TMG) with (or without) trimethylaluminum (TMA) in group III flow and NH3 in group V stream. The optical characteristics of GaN films deposited on (11 (2) over bar0) Al2O3 substrates were found to be comparable to those of GaN films grown on (0 0 0 1) Al2O3 substrates under the same growth conditions. It appears that an increment of V/III ratio allows to improve the morphological and optical properties of a GaN film deposited on the (11 (2) over bar0) Al2O3 substrate. The best quality GaN films were achieved at a V/III ratio of 10 400 with a quenched yellow luminescence and an enhanced room temperature (RT) near band edge photoluminescence (PL) emission having a linewidth of similar to 120 meV. (c) 2005 Elsevier B.V. All rights reserved.