Plasma-assisted MBE of InGaN epilayers with atomically smooth and nanocolumnar morphology, grown on MOVPE GaN/Al 2O 3 templates

Abstract

We report on the state-of-the-art parameters of GaN PA MBE layers grown on GaN/c-Al 2O 3 MOVPE templates and compare the structural and optical properties of In x Ga 1− x N layers grown under different conditions on top of the GaN–MBE/GaN–MOVPE/Al 2O 3 buffer structures. Atomically smooth and structurally perfect GaN and In 0.14Ga 0.86N epilayers have been achieved. The relatively low values of indium incorporation efficiency α In in the InGaN layers grown on templates limits the maximum growth temperature and In-content that are necessary to achieve bright RT luminescence in the long-wavelength spectral range (>500 nm). It has been proposed that implementation of N-rich growth conditions resulting in the nanocolumnar growth morphology increases α In and facilitates inhomogeneous spatial distribution of In in InGaN alloys, which play a crucial role in the red shift of the RT luminescence up to 510 nm and enhancement of its intensity.