Imaging ambipolar two-dimensional carriers induced by the spontaneous electric polarization of a polar semiconductor BiTeI

Y. Kohsaka, M. Kanou, H. Takagi, T. Hanaguri, and T. Sasagawa
Phys. Rev. B 91, 245312 – Published 26 June 2015
PDFHTMLExport Citation

Abstract

Two-dimensional (2D) mobile carriers are a wellspring of quantum phenomena. Among various 2D-carrier systems, such as field effect transistors and heterostructures, polar materials hold a unique potential; the spontaneous electric polarization in the bulk could generate positive and negative 2D carriers at the surface. Although several experiments have shown ambipolar carriers at the surface of a polar semiconductor BiTeI, their origin is yet to be specified. Here we provide compelling experimental evidences that the ambipolar 2D carriers at the surface of BiTeI are induced by the spontaneous electric polarization. By imaging electron standing waves with spectroscopic imaging scanning tunneling microscopy, we find that positive or negative carriers with Rashba-type spin splitting emerge at the surface corresponding to the polar directions in the bulk. The electron densities at the surface are constant independently of those in the bulk, corroborating that the 2D carriers are induced by the spontaneous electric polarization. We also successfully image that lateral pn junctions are formed along the boundaries of submicron-scale domains with opposite polar directions. Our study presents a means to endow nonvolatile, spin-polarized, and ambipolar 2D carriers as well as, without elaborate fabrication, lateral pn junctions of those carriers at atomically sharp interfaces.

  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
1 More
  • Received 19 February 2015
  • Revised 5 June 2015

DOI:https://doi.org/10.1103/PhysRevB.91.245312

©2015 American Physical Society

Authors & Affiliations

Y. Kohsaka1,2,*, M. Kanou3, H. Takagi2,4,5,6, T. Hanaguri1, and T. Sasagawa3

  • 1RIKEN Center for Emergent Matter Science, Wako, Saitama 351-0198, Japan
  • 2RIKEN Advanced Science Institute, Wako, Saitama 351-0198, Japan
  • 3Materials and Structures Laboratory, Tokyo Institute of Technology, Yokohama, Kanagawa 226-8503, Japan
  • 4RIKEN Magnetic Materials Laboratory, Wako, Saitama 351-0198, Japan
  • 5Department of Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
  • 6Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, 70569 Stuttgart, Germany

  • *kohsaka@riken.jp

Article Text (Subscription Required)

Click to Expand

Supplemental Material (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand
Issue

Vol. 91, Iss. 24 — 15 June 2015

Reuse & Permissions
Access Options
Author publication services for translation and copyediting assistance advertisement

Authorization Required


×
×

Images

×

Sign up to receive regular email alerts from Physical Review B

Log In

Cancel
×

Search


Article Lookup

Paste a citation or DOI

Enter a citation
×