Distinct ultrafast carrier dynamics governed by spin filtering in bulk and single-layer WSe2

ORAL

Abstract

Carrier dynamics in a semiconductor following pulsed optical excitation is relevant to ultrafast optoelectronic applications. We report herein a comparative study of bulk WSe2 and single-layer (SL) WSe2 grown on bilayer-graphene-terminated SiC. Subtle dimensional effects lead to substantial differences in the transient response as revealed by time-resolved angle-resolved photoemission spectroscopy (TRARPES) measurements. The conduction band minimum in bulk WSe2, populated by optical pumping, decays promptly. The corresponding decay for SL WSe2 is more complex but overall much slower due to spin filtering arising from the lack of space inversion symmetry. Concurrent measurements of the valence bands show longer but different response times arising from lattice excitation, carrier transport, and dissipation. These results illustrate the various time scales and processes at work for carrier and band structure evolution.

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Presenters

  • Ro-Ya Liu

    University of Illinois at Urbana-Champaign, Institute of Physics, Academia Sinica, Department of Physics, University of Illinois-Urbana-Champaign

Authors

  • Ro-Ya Liu

    University of Illinois at Urbana-Champaign, Institute of Physics, Academia Sinica, Department of Physics, University of Illinois-Urbana-Champaign

  • Meng-Kai Lin

    Department of Physics, University of Illinois Urbana-Champaign, University of Illinois at Urbana-Champaign, Physics, University of Illinois at Urbana-Champaign, Department of Physics, University of Illinois-Urbana-Champaign

  • Peng Chen

    Physics, University of Illinois at Urbana-Champaign, Department of Physics, University of Illinois-Urbana-Champaign

  • Takeshi Suzuki

    Institute for Solid State Physics, University of Tokyo

  • Philippa Clark

    Photon Science Institute, University of Manchester

  • Nathan Lewis

    Photon Science Institute, University of Manchester

  • Cephise Cacho

    Diamond Light Source, STFC Rutherford Appleton Laboratory

  • Emma Springate

    Central Laser Facility, STFC Rutherford Appleton Laboratory

  • Chia-Seng Chang

    Institute of Physics, Academia Sinica, Taipei, Taiwan, Institute of Physics, Academia Sinica

  • Kozo Okazaki

    Institute for Solid State Physics, University of Tokyo, Institute for Solid State Physics, The University of Tokyo

  • Wendy Flavell

    Photon Science Institute, University of Manchester

  • Iwao Matsuda

    Institute for Solid State Physics, University of Tokyo

  • Tai-Chang Chiang

    University of Illinois at Urbana-Champaign, Physics, University of Illinois, Department of Physics, University of Illinois Urbana-Champaign, Physics, University of Illinois at Urbana-Champaign, Department of Physics, University of Illinois-Urbana-Champaign, Physics, University of Illinois Urbana-Champaign