Indium gallium oxide-based thin-film transistors (TFTs) are formed using rf magnetron sputtering of the channel layer. These TFTs exhibit qualitatively ideal characteristics, including excellent drain current saturation. Various deposition parameters, annealing treatments, and stoichiometries are explored. Varying them oxygen partial pressure is found to have a significant effect on device. performance. Decreasing the oxygen partial pressure increases the incremental channel mobility mu(inc) while decreasing (becomes more negative) the turn-on voltage V-on. Increasing indium concentration of the channel material increases mu(inc), while decreasing V-on. The maximum value of mu(inc), similar to 27 cm(2) V-1 s(-1), is obtained by annealing at 600 degrees C, with corresponding V-on and drain current on-to-off ratio values of approximately -14 V and > 10(6), respectively. Additionally, TFTs subjected to a 200 degrees C postdeposition annealing exhibit mu(inc) and V-on of similar to 19 cm(2) V-1 s(-1) and 2 V, respectively. (c) 2006 American Vacuum Society.