Thin-film transistors (TFTs) were fabricated with an aluminum oxide-doped tin oxide (SAO) channel, deposited by cosputtering SnO2 and Al2O3 targets. The effect of the Al2O3 content on the device performance of the SnOx-based TFTs was investigated. The TFTs with a nondoped SnOx channel did not show a promising performance. However, the field-effect mobility and threshold voltage of the SAO TFTs with an Al concentration of about 0.9 atom % were improved to similar to 3.8 cm(2)/V s and similar to 0.6 V, respectively. This improved device performance was attributed to the greatly reduced carrier concentration induced by the carrier trapping at the Al impurity sites. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3194251] All rights reserved.