Vacancy Reduction, Structural and Electronic Studies of Epitaxial Films of Topological Insulators

ORAL

Abstract

We have developed methods for controlling the carrier concentration via a vacancy concentration reduction procedure in the MBE grown epitaxial topological insulator (TI) thin film on various substrates to reach the intrinsic features of TI. Our single crystalline TI thin films allowed us to systematically investigate the nature of coherent transport in this system. For structural characterization of TI thin films, various non-distractive methods, such as x-ray and electron based diffraction techniques, were used as a local probe to understand the long-, short-range atomic ordering and also lattice site occupation. Besides the improved electronic properties of the layers, as grown crystalline films density increased by 20{\%} due to controlled vacancy reduction, determined by in-situ x-ray diffraction. Furthermore, correlation of vacancies and Se ion migration was observed to be the likely reason for lowering the carrier concentration. Our study also shows the dependence of carrier mobility and the vacancy concentration which has been optimized.

*Work supported by MIT Lincoln Laboratory, ONR grant N00014-09-1-0177, and NSF grant DMR 0504158.

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Authors

  • F. Katmis

    • MIT, Francis Bitter Magnet Lab
    • Francis Bitter Magnet Lab, MIT, Cambridge, MA
    • MIT
    • Department of Physics, MIT, Cambridge, USA

  • V. Fatemi

    • MIT
    • Department of Physics, MIT
    • Department of Physics, MIT, Cambridge, USA

  • H. Steinberg

    • MIT
    • Department of Physics, MIT, Cambridge, USA

  • L. Orona

    • Department of Physics, MIT, Cambridge, USA

  • Peng Wei

    • MIT, Francis Bitter Magnet Lab
    • Francis Bitter Magnet Lab, MIT, Cambridge, MA
    • FBML, MIT, Cambridge, USA
    • FBML, MIT

  • Pablo Jarillo-Herrero

    • MIT
    • Massachusetts Institute of Techology
    • Physics Department, MIT, Cambridge, MA
    • Department of Physics, MIT, Cambridge, USA
    • Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139 USA
    • Massachusetts Institute of Technology

  • Jagadeesh S. Moodera

    • Massachusetts Institute of Technology
    • MIT, Francis Bitter Magnet Lab
    • Francis Bitter Magnet Lab and Physics Department, MIT, Cambridge, MA
    • MIT
    • Department of Physics, MIT, Cambridge, USA
    • Francis Bitter Magnet Lab.
    • FBML and Physics Dept., MIT