A series of ZnO films were deposited on c-plane sapphire substrates having different buffer layer thicknesses between 50 and 500 Angstrom by radio-frequency (rf) magnetron sputtering. Scanning electron microscopy (SEM) was utilized to investigate the surface morphology of ZnO films. T he crystallinity of ZnO films was investigated by the double-crystal X-ray diffractometry (DCXRD). The optical properties of ZnO films were also investigated using low-temperature (LT) photoluminescence (PL). It was found that the surface morphology, structural and optical properties of the films depended on the thickness of the buffer layer. The films deposited on the 100 Angstrom thick ZnO buffer layer exhibit the good structural and optical properties with a very smooth surface. (C) 2003 Elsevier Science B.V. All rights reserved.