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 In
₂
O
₃
and SnO
₂
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
V
^-1
s
^-1
, a subthreshold swing of 0.33 V/decade, an ON/OFF-current ratio of 1 × 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.