The annealing effect on the surface and the microstructural properties of ZnO thin films grown on p-Si (100) substrates by radio-frequency magnetron sputtering have been investigated using atomic force microscopy (AFM), X-ray diffraction (XRD), and transmission electron microscopy (TEM) measurements. The AFM images and the XRD patterns showed that the crystallinity of the annealed ZnO films was enhanced by annealing in comparison with that of the as-grown ZnO films, and XRD patterns, pole figures, and TEM images showed that the as-grown and the annealed ZnO films grown on Si (100) substrates had a c-axis preferential orientation in the [0001] crystal direction. These results indicate that the surface and the microstructural qualities of the ZnO films grown on p-Si (100) substrates are improved by thermal treatment. (C) 2003 Elsevier B.V. All rights reserved.