The influence of low-pressure O-2 and Zn atmosphere on the luminescent properties of ZnO phosphor was investigated. The intensity of the green emission of ZnO phosphor was enhanced when the samples were annealed in low-pressure O-2, whereas Zn atmosphere annealing reduced the emission intensity. The equilibrium analysis of native defects supported that a donor-acceptor recombination process may be applied to the green emission, in which oxygen vacancy and Zn vacancy played the roles of the donor and the acceptor, respectively. The existence of V-O(center dot) was caught by electronic paramagnetic resonance measurements. (c) 2006 The Electrochemical Society.