Characterization of thermal annealed n-ZnO/p-GaN/Al₂O ₃

This paper reports the effects of post thermal annealing in air and N ₂ on the structural and optical properties of zinc oxide (ZnO) films deposited on a p-GaN substrate. The properties of annealed ZnO/GaN/Al ₂O₃ films were investigated by atomic force microscopy (AFM), X-ray diffraction (XRD), transmission electron microscopy (TEM), photoluminescence (PL), and Auger electron spectroscopy (AES). Our experiments demonstrated that the ZnO film annealed in N₂ had better structural properties than as-deposited ZnO film. When annealed in air, the optical property of ZnO film was improved by the oxygen from ambient air, although the structural properties were somewhat poor and the interface of ZnO and GaN was degraded by the formation of a Ga-O mixed phase.