In-situ electrostatic doping in 2D semiconductor heterostructures determined by micro-ARPES

ORAL

Abstract

Understanding the behavior of 2D devices calls for probing the local electronic spectrum and how it is affected by bias. The most powerful technique for determining band structure is angle-resolved photoemission (ARPES), which can now be applied to micron-scale, electrically contacted samples, for example at Spectromicroscopy beamline, Elettra . Using this facility, and by designing samples with electron-transparent monolayer graphene or hBN caps for protection, we have studied heterostructures of WS$_2$, MoS$_2$, MoSe$_2$ and graphene that are back-gated with a thin graphite electrode through an h-BN dielectric. Using the gate we reversibly tuned in-situ in the ARPES chamber the carrier density in graphene up to $\pm$2$\times$ 10$^{13}$ cm$^{-2}$ and measured field induced changes in band alignments in heterostructures. We were also able to electrostatically populate the conduction band in MoS$_2$, revealing a direct gap at the K-point of 2.1 $\pm$ 0.1 eV, in good agreement with recent STM measurements.

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Authors

  • Paul Nguyen

    Univ of Washington, Department of Physics, University of Washington, University of Washington

  • Neil Wilson

    University of Warwick

  • Natalie Teutsch

    University of Warwick

  • Gabriel Constantinescu

    University of Cambridge, UK, University of Cambridge

  • Viktor Kandyba

    Sincrotrone Elettra Trieste

  • Alexey Barinov

    Sincrotrone Elettra Trieste

  • Nicholas Hine

    University of Warwick, UK, University of Warwick

  • Xiaodong Xu

    University of Wasington, University of Washington, Univ of Washington, Department of Physics, University of Washington, University of Washington, Seattle, USA.

  • David Cobden

    Department of Physics, University of Washington, Department of Physics, University of Washington, Seattle, WA 98195, USA, Univ of Washington, University of Washington