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

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 degrees 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)V(-1)s(-1), a subthreshold swing of 0.33 V/decade, an ON/OFF-current ratio of >1 x 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.