Enhancement of Ultraviolet and Visible Emissions of ZnO with Zn by Thermal Treatment

Pure ZnO was prepared at lower temperature (30 °C) by electrodepositing at higher temperature (50 °C), and Zn-incorporated ZnO was prepared. They were thermally treated in oxygen at different temperatures to investigate their optical characteristics using photoluminescence. The UV band from the band-edge emission is observed in the treated Zn incorporated ZnO but not in the thermally treated pure ZnO. The UV emission is proposed to be from the ZnO oxidized from Zn. The peak intensity of visible emission for the thermally treated Zn-incorporated ZnO is about 10 times that of emission from pure ZnO at 900 °C. The blue-green band of visible emission results from the defects in ZnO oxidized from Zn and, its enhancement may be related to the thermal stress and the improvement of the interface between ZnO and ZnO oxidized from Zn.