We report here the performance of amorphous oxide transparent thin film transistors (TFTs) fabricated using DC magnetron sputter techniques at room temperature. Amorphous indium zinc oxide (a-IZO, In2O3:ZnO, 90:10 wt.%) and high dielectric constant hafnium oxide (HfO2) films were deposited for the semiconducting channel and gate insulator under a mixture of ambient argon and oxygen gas, respectively. The reported transparent TFT structure was a bottom-gate type, consisting of indium-tin-oxide and aluminium as gate electrode and source/drain electrodes, respectively. The optical transmittance of a-IZO films in the visible region was greater than 84%. The a-IZO TFTs showed that the field effect saturation mobility, I-on/I-off ratio, sub-threshold swing, and threshold voltage were extracted to give 13.09 cm(2)/V-s, 4 x 10(5), 0.42 V/decade, and 3.54 V. respectively. The reported a-IZO TFT with high dielectric constant HfO2 gate dielectric sputtered at room temperature presents high quality characteristics, which can be used as good candidate for the application of low-temperature fabricated optoelectronic devices on organic flexible substrates. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.