We have deposited the GaN films on Si(0 0 1) substrate using the ZnO buffer layers at room temperature by the radio frequency (rf) magnetron sputtering method. The ZnO buffer layer thickness affected the structural properties of GaN films. With a sufficiently thick ZnO layer, we have obtained a c-axis-oriented GaN/ZnO thin film on Si with the XRD full-width at half-maximum (FWHM) of 0.22degrees and root-mean-square (RMS) surface roughness of about 22 Angstrom. (C) 2004 Elsevier B.V. All rights reserved.