Influence of oxygen partial pressure in In-Sn-Ga-O thin-film transistors at a low temperature

Abstract

We examined the electrical properties of low-temperature-processed top-gate In-Sn-Ga-O (ITGO) thin-film transistors (TFTs) by rf/dc-sputtering with different oxygen partial pressures (PO2). As PO2 changed from 0 to 50.0%, the ITGO TFT showed various electrical characteristics such as from conductor-like behavior to transfer curves with positive-shifted threshold voltages (Vth). The TFT at PO2 of 25.0% afforded the best performance, exhibiting field-effect mobility of 14.8 cm(2)V(-1)s(-1), Vth of 0.56 V, and subthreshold slope of 0.16 Vdec(-1) with reasonable electrical stability for gate bias stress. From various analysis techniques, we found that the TFT characteristics and the electrical stability strongly depended on the metal-oxygen surface states of the ITGO films influenced by PO2 during the sputtering process. (C) 2019 Elsevier B.V. All rights reserved.