Effects of annealing process on characteristics of fully transparent zinc tin oxide thin-film transistor

Annealing effect on the performance of fully transparent thin-film transistor (TTFT), in which zinc tin oxide (ZnSnO) is used as the channel material and SiO₂ as the gate insulator, is investigated. The ZnSnO active layer is deposited by radio frequency magnetron sputtering while a SiO₂ gate insulator is formed by plasma-enhanced chemical vapor deposition. The saturation field-effect mobility and on/off ratio of the TTFT are improved by low temperature annealing in vacuum. Maximum saturation field-effect mobility and on/off ratio of 56.2 cm²/(V·s) and 3×10⁵ are obtained, respectively. The transfer characteristics of the ZnSnO TFT are simulated using an analytical model and good agreement between measured and the calculated transfer characteristics is demonstrated.