Fabrication of high-performance ultra-thin-body SnO2 thin-film transistors using microwave-irradiation post-deposition annealing

We report on the fabrication of high-performance ultra-thin-body (UTB) SnO2 thin-film transistors (TFTs) using microwave-irradiation post-deposition annealing (PDA) at a low process temperature (<100 °C). We confirm that the electrical characteristics of SnO2 TFTs become drastically enhanced below a body thickness of 10 nm. The microwave-annealed UTB SnO2 TFTs with a thickness of 5 nm exhibited increased optical transmittance, as well as remarkable transfer characteristics: a high mobility of 35.4 cm2 V−1 s−1, a drain current on/off ratio of 4.5 × 107, a steep subthreshold gate voltage swing of 623 mV/dec, and a clear enhancement-mode behavior. Additionally, the microwave-annealed SnO2 TFTs exhibited a better positive gate-bias stress/negative gate-bias stress immunity than thermally annealed SnO2 TFTs. Therefore, the thickness of the UTB SnO2 TFTs, as well as the microwave-annealing process, are both shown to be essential for transparent and flexible display technology.