ZnO films were successfully deposited on c-plane sapphire substrates by low-pressure MOCVD using Diethylzinc (DEZn) and oxygen. The c-axis oriented ZnO films were grown on sapphire at the temperature of 600degreesC with different ZnO buffer layer thicknesses between 5 and 55 nm. The effects of ZnO buffer layer on crystallinity, surface morphology and optical properties of ZnO films were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and photo luminescence (PL) spectrum, respectively. It was found that surface morphology, structural and optical properties of the films depended on the thickness of the buffer layer. The ZnO film grown on the 15 nm thick ZnO buffer layer shows a flat and dense surface, the good structural and optical properties. (C) 2003 Elsevier B.V. All rights reserved.