Role of Electron Donation of TiO₂ Gate Interface for Developing Solution-Processed High-Performance One-Volt Metal-Oxide Thin-Film Transistor Using Ion-Conducting Gate Dielectric

High-performance solution-processed one-volt metal-oxide thin-film transistor (TFT) has been fabricated onto highly p-doped silicon (p ++ -Si) substrate with sol–gel-derived ion-conducting gate dielectric by using electron-donating TiO 2 gate interface. A comparative electrical characterization of two different TFTs with TiO 2 and Al 2 O 3 gate interface device reveals that n-type TiO 2 works as an electron donor to the semiconductor/dielectric interface trap state. As a consequence, subthreshold swing (SS) of the TiO 2 interface device reduces significantly by keeping threshold voltage closer to zero enabling to achieve significantly higher-performance one-volt TFT with respect to “without TiO 2 ” and “with Al 2 O 3 ” interface devices. Additionally, depleted layer of p ++ -Si(111)/TiO 2 interface reduces gate leakage current significantly that helps to improve the on/off ratio of the device. Specifically, in this report, one-volt TFT with indium zinc oxide semiconductor has been fabricated by using Li 5 AlO 4 dielectric with TiO 2 gate interface that achieved electron mobility of 32 cm 2 /(V·s) with on/off ratio of 5 × 10 5 and subthreshold swing of 110 mV/dec. This investigation provides a feasible direction toward the development of high-performance, low-voltage TFT fabrication with various materials combination.