High-mobility and high-reliability Zn-incorporated amorphous In₂O₃-based thin-film transistors

Abstract

Polycrystalline indium oxide-based thin film transistors (In2O3 TFTs) have attracted considerable attention because of high field effect mobility (μFE ~100 cm2 V−1 s−1). However, In2O3 TFTs exhibit poor reliability owing to the adsorption and/or desorption of gas molecules at the grain boundaries. The incorporation of Zn suppresses the crystallization of In2O3. Herein, we systematically studied the effect of Zn incorporation into In2O3 TFTs. The crystallization of In2O3 was suppressed when the Zn concentration ranging from 25% to 68%. Amorphous IZO TFTs with 25% Zn exhibited the highest μFE of 41 cm2 V−1 s−1 and excellent reliability. In contrast, polycrystalline IZO TFTs showed a low μFE <12 cm2 V−1 s−1 due to the formation of grain boundaries, and poor reliability after positive gate bias, mostly due to electron trapping at the polycrystalline/insulator interface. These results render an approach to realize In2O3 TFTs that show reasonably high μFE and excellent reliability.