Tunability of p- and n-channel TiOx thin film transistors

To acquire device-quality TiOx films usually needs high-temperature growth or additional post-thermal treatment. However, both processes make it very difficult to form the p-type TiOx even under oxygen-poor growth condition. With the aid of high energy generated by high power impulse magnetron sputtering (HIPIMS), a highly stable p-type TiOx film with good quality can be achieved. In this research, by varying the oxygen flow rate, p-type γ-TiO and n-type TiO2 films were both prepared by HIPIMS. Furthermore, p- and n-type thin film transistors employing γ-TiO and TiO2 as channel layers possess the field-effect carrier mobilities of 0.2 and 0.7 cm2/Vs, while their on/off current ratios are 1.7 × 104 and 2.5 × 105, respectively. The first presented p-type γ-TiO TFT is a major breakthrough for fabricating the TiOx-based p-n combinational devices. Additionally, our work also confirms HIPIMS offers the possibility of growing both p- and n-type conductive oxides, significantly expanding the practical usage of this technique.