This is a report on the effect of a ZnO buffer layer on the microstructures and optical properties of MgZnO thin films grown on Si (100) substrates by radio frequency magnetron sputtering. For the sample without the ZnO buffer layer, the microstructural analyses carried out by X-ray diffraction (XRD) and transmission electron microscopy (TEM) revealed the formation Of Mg(2)Si in the interface between the Si substrate and the MgZnO thin film. Mg(2)Si induced the random oriented polycrystalline MgZnO thin film. For the sample with the ZnO buffer layer, a few Mg(2)Si were observed. An epitaxial relationship between the Si substrate and the MgZnO thin film was formed. In both samples, the photoluminescence (PL) investigation showed a small blue shift of the emission peak, which was owing to the incorporation of Mg atoms in ZnO by co-sputtering the MgO and ZnO targets. In addition, the sample with the ZnO buffer layer showed the enhanced PL intensity, when compared with the sample without the buffer layer. (C) 2009 Elsevier B.V. All rights reserved.