We report on the performance of the thin film transistors (TFTs) using ZnO as an active channel layer grown by using radio frequency (rf) magnetron sputtering technique. The TFT device structure used in this study was a bottom gate type, which consists of SiNx as a gate insulator and indium tin oxide (ITO) as a gate deposited onto Corning glass substrates. These ZnO TFTs had a saturation field effect mobility of about 31 cm2/V s, an on to off ratio of greater than 105, the off current of less than 10-10 A, and a threshold voltage of 9 V at a maximum device processing temperature of 300 °C. This TFT had a channel width of 400 μm and channel length of 10 μm. Moreover, the SiNx dielectric layer was found to be optimum for the high performance ZnO based TFTs because of the very low leakage current and good interface between the channel layer and gate material. © 2007 Elsevier Ltd. All rights reserved.