ZnO films were deposited on c-plane sapphire substrates by metal-organic chemical vapor deposition (MOCVD). Thermal annealing was performed under growth conditions and in oxygen atmosphere. The photoluminescence (PL) spectra of the as-grown, annealed under growth conditions and oxygen atmosphere ZnO films were studied. The intensity of the ultraviolet (UV) emission peak from exciton transitions in the sample annealed under growth conditions increased, while the intensity of the deep-level emission peak decreased. For the sample annealed in oxygen atmosphere, the peak related to deep level strongly increased. Through the analysis and calculation, we suggest that the deep-level luminescence centers are zinc vacancy (V-Zn) and antisite defect (O-Zn), and the centers in the film annealed in oxygen atmosphere increase. (C) 2003 Elsevier B.V. All rights reserved.