Thin film transistors (TFTs) with indium zinc tin-oxide (IZTO) dual-channel layers were fabricated on heavily-doped p-type Si substrates by using a tilted dual-target radio-frequency magnetron sputtering system. The number of oxygen vacancies in the IZTO channel layer decreased with increasing oxygen partial pressure, resulting in a decrease in the conductivity. The threshold voltage (Vth) shifted toward positive gate-source voltage with increasing oxygen partial pressure for the growth of the IZTO layer because of a decrease in the carrier concentration. The Vth, the mobility, the on/off-current ratio, and the subthreshold swing of the dual-channel IZTO TFTs were 3.5 V, 7.1 cm(2)/V s, 13 V/decade, and 8.2 x 10(6), respectively, which was enhanced by utilizing dual-channel layers consisting of a top channel deposited at a high oxygen partial pressure and a bottom channel deposited at a low oxygen partial pressure. (C) 2014 Elsevier B.V. All rights reserved.