Field-induced water electrolysis switches an oxide semiconductor from an insulator to a metal

TL;DR

This study demonstrates that applying a positive gate voltage to a SrTiO3 oxide semiconductor with a water-infiltrated nanoporous glass gate insulator induces water electrolysis and electrochemical reduction, transforming it from an insulator to a highly conductive metal with thermoelectric properties.

Contribution

The paper introduces a novel method of switching an oxide semiconductor from insulator to metal using water electrolysis in a field-effect transistor configuration.

Findings

Formation of a ~3 nm metal layer on SrTiO3 surface

High electron concentration of 10^15-10^16 cm^-2 in the metal layer

Exhibition of exotic thermoelectric behavior

Abstract

Here we demonstrate that water-infiltrated nanoporous glass electrically switches an oxide semiconductor from an insulator to metal. We fabricated the field effect transistor structure on an oxide semiconductor, SrTiO3, using 100%-water-infiltrated nanoporous glass - amorphous 12CaO*7Al2O3 - as the gate insulator. For positive gate voltage, electron accumulation, water electrolysis and electrochemical reduction occur successively on the SrTiO3 surface at room temperature, leading to the formation of a thin (~3 nm) metal layer with an extremely high electron concentration of 10^15-10^16 cm^-2, which exhibits exotic thermoelectric behaviour.