Growth of In-rich InGaN on InN template by radio-frequency plasma assisted molecular beam epitaxy

Abstract

High-quality epitaxial InN films have been employed as underlying templates for the growth of In-rich In x Ga 1− x N (0.71⩽ x⩽0.90) films by radio-frequency plasma assisted molecular beam epitaxy. The epitaxial InN films (InN templates) with the thickness of 500 nm were grown on (0 0 0 1) sapphire substrates with a low-temperature deposited 10 nm thick InN (LT-InN) buffer layer, and then In-rich In x Ga 1− x N films with the thickness of 250 nm were grown on these InN templates. As compared with In-rich In x Ga 1− x N films grown directly on the LT-InN buffer layers, the In-rich In x Ga 1− x N films grown on the InN templates showed a decrease in full-width at half-maximum of the (0 0 0 2) X-ray rocking curves. It was found that the insertion of the InN template was very effective in improving the crystalline quality of In-rich In x Ga 1− x N. Optical properties were also investigated by photoluminescence. Lattice distortion of the In-rich In x Ga 1− x N films induced by the underlying InN templates is also discussed.