Indium Oxide Thin-Film Transistors Fabricated by RF Sputtering at Room Temperature

Thin-film transistors (TFTs) were fabricated using an indium oxide (In₂O₃) thin film as the n-channel active layer by RF sputtering at room temperature. The TFTs showed a thickness-dependent performance in the range of 48-8 nm, which is ascribed to the total carrier number in the active layer. Optimum device performance at 8-nm-thick In₂O₃ TFTs had a field-effect mobility of 15.3 cm² · V^-1 · s^-1, a threshold voltage of 3.1 V, an ON-OFF current ratio of 2.2 × 10⁸, a subthreshold gate voltage swing of 0.25 V · decade^-1, and, most importantly, a normally OFF characteristic. These results suggest that sputter-deposited In₂O₃ is a promising candidate for high-performance TFTs for transparent and flexible electronics.