The ZnO films were deposited on (0 0 I)Si substrate by metal-organic chemical vapor deposition (MOCVD). Annealing was performed in air for 60 min at 800degreesC. The X-ray diffraction patterns of the samples showed sharp diffraction peaks for ZnO(0 0 2), which indicated that the films were highly c-axis oriented. Zn and O elements in the as-deposited ZnO film were investigated and compared with those in the annealed ZnO film by using X-ray Photoelectron Spectroscopy (XPS). XPS spectra showed that ZnO films changed from Zn-rich to O-rich after being annealed. (C) 2003 Elsevier Science B.V. All rights reserved.