High mobility transparent thin-film transistors with amorphous zinc tin oxide channel layer

Transparent thin-film transistors (TTFTs) with an amorphous zinc tin oxide channel layer formed via rf magnetron sputter deposition are demonstrated. Field-effect mobilities of 5–15 and $20–50cm2V−1s−1$ are obtained for devices post-deposition annealed at 300 and $600°C$⁠, respectively. TTFTs processed at 300 and $600°C$ yield devices with turn-on voltage of 0–15 and $−5–5V$⁠, respectively. Under both processing conditions, a drain current on-to-off ratio greater than $107$ is obtained. Zinc tin oxide is one example of a new class of high performance TTFT channel materials involving amorphous oxides composed of heavy-metal cations with $(n−1)d10ns0$ $(n⩾4)$ electronic configurations.