Amorphous Indium Tin Oxide Thin-Film Transistors Fabricated by Cosputtering Technique

Abstract

Amorphous indium tin oxide (a-ITO) thin-film transistors (TFTs) were fabricated with the channel layer deposited by the cosputtering of In2O3 and SnO2 ceramic targets. It is shown that the cosputter-deposited ITO film for the channel layer well keeps in the amorphous structure even after being annealed at 300° if the sputtering powers of the two targets are properly selected. The fabricated a-ITO TFTs in the cosputtering technique show a high device performance, including a field-effect mobility of 25.9 cm $^{2}\text{V}^{-1}\text{s}^{-1}$ , a subthreshold swing of 0.33 V/decade, an ON/OFF-current ratio of $> 1 \times 10^{9}$ , and a desirable threshold voltage variation range. In addition, an acceptable characteristic stability under electrical stress is also observed in the passivated and annealed a-ITO TFTs.