MOVPE growth of thick homogeneous InGaN directly on sapphire substrate using AlN buffer layer

Abstract InGaN films have usually been grown on GaN epitaxial layers but it is difficult to grow the thick InGaN films on GaN because of strong stress induced by large lattice mismatch between InGaN and GaN. The thick InGaN films grown on GaN have poor surface morphologies. In this paper it is described that the growth of thick InGaN films of a few microns thickness has successfully been achieved directly on sapphire substrates using AlN buffer layers. On AlN buffer layers homogeneous InGaN with 2.5 μm thickness and large indium mole fraction of 0.2 could be grown. The growth rate of 2.5 μm/h is much larger than has been reported previously.