Ambipolar transport in bulk crystals of a topological insulator by gating with ionic liquid

Kouji Segawa, Zhi Ren, Satoshi Sasaki, Tetsuya Tsuda, Susumu Kuwabata, and Yoichi Ando
Phys. Rev. B 86, 075306 – Published 14 August 2012

Abstract

We report that the ionic-liquid gating of bulk single crystals of a topological insulator can control the type of the surface carriers and even results in ambipolar transport. This was made possible by the use of a highly bulk-insulating BiSbTeSe2 system where the chemical potential is located close to both the surface Dirac point and the middle of the bulk band gap. Thanks to the use of ionic liquid, the control of the surface chemical potential by gating was possible on the whole surface of a bulk three-dimensional sample, opening new experimental opportunities for topological insulators. In addition, our data suggest the existence of a nearly reversible electrochemical reaction that causes bulk carrier doping into the crystal during the ionic-liquid gating process.

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  • Received 9 March 2012

DOI:https://doi.org/10.1103/PhysRevB.86.075306

©2012 American Physical Society

Authors & Affiliations

Kouji Segawa1,*, Zhi Ren1, Satoshi Sasaki1, Tetsuya Tsuda2,3, Susumu Kuwabata3,4, and Yoichi Ando1,†

  • 1Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan
  • 2Frontier Research Base for Global Young Researchers, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan
  • 3Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan
  • 4Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Kawaguchi, Saitama 332-0012, Japan

  • *segawa@sanken.osaka-u.ac.jp
  • Corresponding author: y_ando@sanken.osaka-u.ac.jp

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Issue

Vol. 86, Iss. 7 — 15 August 2012

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