High-mobility p-type NiOx thin-film transistors processed at low temperatures with Al2O3 high-k dielectric†
Although there are a few research studies on solution-processed p-channel oxide thin-film transistors (TFTs), the strict fabrication conditions and the poor electrical properties have limited their applications in low-power complementary metal oxide semiconductor (CMOS) electronics. Here, the application of the polyol reduction method for processing p-type CuxO and NiOx channel layers and their implementation in TFT devices are reported. The optimized CuxO and NiOx TFTs were achieved at low annealing temperatures (∼300 °C) and exhibited decent electrical properties. Encouraged by the inspiring results obtained on SiO2/Si substrates, the TFT performance was further optimized by device engineering, employing high-k AlOx as the gate dielectric. The fully solution-processed NiOx/AlOx TFT could be operated at a low voltage of 3.5 V and exhibits a high hole mobility of around 25 cm2 V−1 s−1. Our work demonstrates the ability to grow high-quality p-type oxide films and devices via the polyol reduction method over large area substrates while at the same time it provides guidelines for further p-type oxide material and device improvements.