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•7Al 2 O 3 nanoporous glass and NaTaO 3 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 threeterminal TFTs with TMOs of vanadium dioxide (VO 2 ), tungsten trioxide (WO 3 ) and strontium cobaltite (SrCoO x ). 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.

Solid-State Electrochemical Protonation of SrCoO2.5 into HxSrCoO2.5 (x = 1, 1.5, and 2)

“…Materials that show nonvolatile control of the optical, electrical, and magnetic properties would be useful as active materials of these advanced memory devices. In this regard, transition-metal oxides (TMOs) are promising active materials of such memory devices since many TMOs show the transition from one crystalline phase to another by electrochemical protonation/reduction/oxidation method, resulting in changes in optoelectronic and magnetic properties. − …”

Surface charge accumulation and electrochemical protonation of transition metal oxides using water-infiltrated nanoporous glass

“…We first review the electronic property modulation of SrTiO 3 and VO 2 using CAN-gated TFTs, and then discuss their different operation mechanism based on the magnitude relationship between E CBM of TMOs and E H2 . Since the development of water-infiltrated CAN gate insulators and the TMO-based multi-functional devices using the CAN-gated TFT structures were reviewed in the previous papers [31][32][33], we herein show the device characteristics of the CAN-gated TFTs by comparing to those of TFTs with water-free gate insulator of a fully dense a-C12A7 film.…”