Cathodoluminescence study of optical properties along the growth direction of ZnO films on GaN substrate

c-plane ZnO films were eptiaxially grown on c-GaN/sapphire substrate by MOCVD. Cathodoluminescence (CL) line scan was performed on the cross-sectional ZnO/GaN films. These CL spectra shapes show a variation along the growth direction with a peak position shift, which can be divided into three stages. The study of the three stages reflects the growth mode alteration from the interface between ZnO and GaN to the surface. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)