Band parameters of 2D semiconductor heterostructures determined by micro-ARPES

ORAL

Abstract

Heterostructures made by stacking monolayers of different 2D materials can have unique properties, such as hosting long-lived polarized interlayer excitons. Understanding these depends on knowledge of the band parameters of both the separate monolayers and the hetero-bilayer. Interlayer hybridization can also produce distinct electronic structure dependent on the relative monolayer crystal orientation. The most powerful technique for determining such properties is angle-resolved photoemission (ARPES), which can now be applied to micron-scale samples at the Spectromicroscopy Elettra Trieste beamline. Using this new facility, combined with careful sample design, we have studied heterostructures of WSe2, MoSe2, WS2 and graphene.~ We determined band offsets, effective masses, and spin-orbit splittings with an energy resolution \textless 50 meV. Interestingly, the bands near the gamma-point in hetero-bilayers oriented near zero degrees are not a superposition of those in the isolated monolayers, but exhibit an additional higher band. However, the valence band edge remains at the K-point, which together with the band offsets is consistent with measurements of strong luminescence from interlayer excitons in MoSe2/WSe2.

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Authors

  • Paul Nguyen

    Department of Physics, University of Washington

  • Neil Wilson

    Department of Physics, University of Warwick

  • Pasqual Rivera

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

  • Kyle Seyler

    Univ of Washington, Department of Physics, University of Washington, No Company Provided

  • Alexey Barinov

    Sincrotrone Elettra Trieste

  • Geetha Balakrishnan

    University of Warwick, Department of Physics, University of Warwick, Department of Physics, University of Wrwick, Dept. of Physics, University of Warwick

  • Xiaodong Xu

    Univ of Washington, Department of Physics, University of Washington, university of washington, seattle, University of Washington

  • David Cobden

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