Abstract

We report on the direct growth of high-In-composition InGaN layers on Si(111) by plasma-assisted molecular beam epitaxy without any buffer layers. In a narrow window of growth conditions, laterally extended, micrometer-sized planar areas are formed together with trenches and holes. Detailed structural and optical analyses reveal that the planar areas comprise the InGaN layer with high and uniform In composition, while the trenches and holes are associated with pure GaN and low-In-composition InGaN. Photoluminescence at low temperature is observed from the high-In-composition InGaN layer, which forms an ohmic contact with a p-Si substrate.