Growth and characterization of ZnO nanowires on p-type GaN

ZnO nanowires were grown by catalyst-free metal-organic vapour-phase epitaxy on top of a p-type GaN buffer. The optical properties of the ZnO nanowires were investigated by temperature-dependent and time-resolved photoluminescence and compared to those of ZnO nanowires directly grown on sapphire. The luminescence intensity decrease with temperature of the nanowires grown on GaN reveals an original behavior since it is constant over 120 K, showing the existence of strong localization centers. In addition, the temperature-dependent decay time measurements indicate a lower density of non-radiative channels for the nanowires grown on GaN.