The effect of oxygen partial pressure on the properties of In2O3-Ga2O3 thin films produced by sputtering at room temperature aimed at thin film transistor (TFT) application is reported in this work. When produced in the absence of oxygen, the films are polycrystalline, while in the presence of oxygen, the films are amorphous. The films' resistivity is tuned between 10(-3) and 10(4) Omega cm. Moreover, the films present a high transmittance (>80%) and a smooth surface (r(rms) = 1.2 nm). The high performance as-produced transistors present high saturation mobility (mu(sat) approximate to 43 cm(2)/V s) and a subthreshold gate-voltage swing of 0.51 V/dec, which is reduced to 0.27 V/dec after 150 degrees C annealing. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3257613] All rights reserved.