Growth of AlGaN and GaN films on (112¯0) Al2O3 substrates and the influence of V/III ratio on the properties of GaN films

AlGaN and GaN films were grown on (112¯0) 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 (112¯0) 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 (112¯0) 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 ∼120 meV.