The nature and impact of ZNO buffer layers on the initial stages of the hydride vapor phase epitaxy of GaN

摘要

The nauture and imapct of ZnO buffer layers on the initial stages of the hydride vapor phase epitaxy (HVPE) of GaN have been studied by xray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), xray diffraction (XRD) and photoluminescence (PL). During pre-growth heating, the surface ZnO layer was found to both desorb from ZnO-coated sapphire and react with the underlying sapphire surface forming a thin ZnAl_2O_4 alloy layer between ZnO and sapphire surface. This ZnO-derived surface promotes the initial nucleation of the GaN and markedly improves material surface morphoogy, quality and growth reproducibility.