MgxZn1-xO alloy films were prepared on sapphire substrates using Ar and N-2 as the sputtering gases. The effect of the sputtering gas on the structural, optical and electrical properties of the MgxZn1-xO films was studied. By using N-2 as the sputtering gas, the MgxZn1-xO film shows p-type conductivity and the band gap is larger than that employing Ar as the sputtering gas. The reason for this phenomenon is thought to be related to the reaction between N-O or N-Zn, and the N-doping. (C) 2007 Elsevier B.V. All rights reserved.