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

Abstract

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 TiO2 gate interface. A comparative electrical characterization of two different TFTs with TiO2 and Al2O3 gate interface device reveals that n-type TiO2 works as an electron donor to the semiconductor/dielectric interface trap state. As a consequence, subthreshold swing (SS) of the TiO2 interface device reduces significantly by keeping threshold voltage closer to zero enabling to achieve significantly higher-performance one-volt TFT with respect to "without TiO2" and "with Al2O3" interface devices. Additionally, depleted layer of p++-Si(111)/TiO2 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 Li5AlO4 dielectric with TiO2 gate interface that achieved electron mobility of 32 cm2/(V·s) with on/off ratio of 5 × 105 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. © 2019 American Chemical Society.