Cathodoluminescence investigations of interfaces in InGaN/GaN/sapphire structures

Scanning electron microscopy and cathodoluminescence (CL) in spot and depth-profiling modes were used to evaluate the in-plane and in-depth uniformity of light emission from InGaN/GaN quantum well (QW) structures. The structures were grown by MOCVD on sapphire with a low-temperature (LT) GaN buffer. Depth-profiling CL investigations were used to identify the observed CL emissions, which show a complicated in-depth evolution. The influence of a LT GaN buffer on the structural and optical properties of the GaN/sapphire interface is discussed.