Photoluminescence properties of ZnO thin films prepared by DC magnetron sputtering

ZnO thin films were prepared by direct current(DC) reactive magnetron sputtering under different oxygen partial pressures.And then the samples were annealed in vacuum at 450 ℃. The effects of the oxygen partial pressures and the treatment of annealing in vacuum on the photoluminescence and the concentration of six intrinsic defects in ZnO thin films such as oxygen vacancy(Vo),zinc vacancy(VZn), antisite oxygen(OZn), antisite zinc(ZnO), interstitial oxygen(Oi) and interstitial zinc(Zni) were studied. The results show that a green photoluminescence peak at 520 nm can be observed in all the samples, whose intensity increases with increasing oxygen partial pressure; for the sample annealed in vacuum, the intensity of the green peak increases as well. The green photoluminescence peak observed in ZnO may be attributed to zinc vacancy, which probably originates from transitions between electrons in the conduction band and zinc vacancy levels, or from transitions between electrons in zinc vacancy levels and up valence band.