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

Hiromichi Ohta; Yukio Sato; Takeharu Kato; Sungwng Kim; Kenji Nomura; Yuichi Ikuhara; Hideo Hosono

doi:10.1038/ncomms1112

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

Nat Commun. 2010 Nov 16:1:118. doi: 10.1038/ncomms1112.

Authors

Hiromichi Ohta¹, Yukio Sato, Takeharu Kato, Sungwng Kim, Kenji Nomura, Yuichi Ikuhara, Hideo Hosono

Affiliation

¹ 1] Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa, Nagoya 464-8603, Japan. [2] PRESTO, Japan Science and Technology Agency, 5 Sanbancho, Chiyoda, Tokyo 102-0075, Japan.

Abstract

Water is composed of two strong electrochemically active agents, H(+) and OH(-) ions, but has not been used as an active electronic material in oxide semiconductors. In this study, we demonstrate that water-infiltrated nanoporous glass electrically switches an oxide semiconductor from insulator to metal. We fabricated a field-effect transistor structure on an oxide semiconductor, SrTiO(3), using water-infiltrated nanoporous glass-amorphous 12CaO·7Al(2)O(3)-as the gate insulator. Positive gate voltage, electron accumulation, water electrolysis and electrochemical reduction occur successively on the SrTiO(3) surface at room temperature. This leads to the formation of a thin (~3 nm) metal layer with an extremely high electron concentration (10(15)-10(16) cm(-2)), which exhibits exotic thermoelectric behaviour. The electron activity of water as it infiltrates nanoporous glass may find many useful applications in electronics or in energy storage.