Oxide-based optical, electrical and magnetic properties switching devices with water-incorporated gate insulator

Abstract

Optical, electrical and magnetic properties of transition metal oxides (TMOs) can be switched by their non-stoichiometry, i.e. oxygen excess/deficiency and protonation. However, the switching classically needs high-temperature heating or electrochemistry in liquid electrolyte, which is unsuitable for device applications. To overcome these difficulties, we have developed thin films of water-incorporated 12CaO•7Al2O3 nanoporous glass and NaTaO3 nanopillar glass. By applying the films to water-incorporated solid gate insulators of three-terminal thin-film transistors (TFTs), the confined water works as a strong reductant (H+)/oxidant (OH-) for the TMO channel, and their electro-optical and electromagnetic properties can be controlled by applying an electric field. Herein, we review our developed water-incorporated gate insulators and their application to three-terminal TFTs with TMOs of vanadium dioxide (VO2), tungsten trioxide (WO3) and strontium cobaltite (SrCoOx). The present approach using a water-incorporated gate insulator provides a novel design concept to develop electrochemically switchable multifunctional devices based on TMOs operating at room temperature.