Low-Voltage InGaZnO Thin-Film Transistors Gated by SiO2 Proton Conducting Films

Abstract

Low-voltage (1.5 V) InGaZnO (IGZO) thin-film transistors (TFTs) gated by the SiO2 proton conducting films were self-assembled by a gradient shadow mask in sputtered self-assembled IGZO channel process. The IGZO TFTs have a high-performance with a large current on/off ratio of ≥1.2×106, a low subthreshold swing of ≤120 mV/decade and a high field-effect mobility of 2.2 ~ 6.9 cm2/V·s. Threshold voltage is tuned by various thicknesses of IGZO channel. Both depletion mode and enhancement mode on the same chip is obtained, which will implement a direct-coupled field-effect transistor logic circuit. Our results demonstrate that the IGZO TFTs are promising logic circuit candidates for portable low-voltage oxide-based devices.