Growth of In-rich InGaN films on sapphire via GaN layer by RF-MBE

Abstract

Growth temperature dependence of In-rich InGaN growth properties for each Ga/(Ga+In) supply ratio by radio-frequency plasma assisted molecular beam epitaxy was investigated. The luminescence property of In-rich InGaN films up to 20% of Ga improved compared with that of InN because their growth temperatures could be set at high and high purity InGaN films were obtained. This effect can be partly interpreted as a result of the larger bond strength of Ga–N than that of In–N. However, the InGaN films tend to be Ga-rich in case of relatively high growth temperatures. Also, InGaN dot-like structures at intermediate composition were grown as a result of the combination effect of phase separation due to the immiscibility of GaN into InN and local strain due to lattice mismatch between InGaN and underlying GaN buffer layer.