Electrical tunability and optical control of valley and spin in WSe2

ORAL

Abstract

Monolayer group VI transition metal dichalcogenides have enormous potential for use in nano- and optoelectronic applications due to their reduced dimensionality and direct bandgap in the visible wavelength range. Their hexagonal structure is graphene-like, but with strong spin-orbit coupling effects. The interesting coupled spin-valley physics has been investigated both theoretically and experimentally based on the single particle picture. Here we investigate the physical properties of valley excitons in monolayer field effect transistor devices via photoluminescence measurements. By tuning the chemical potential to control exciton species, we are able to investigate the optical selection rules, photo-excitation energy dependence, and temperature dependence of individual excitons. These studies reveal the fine structures of valley excitons due to the electron-electron interactions, electron-phonon interactions, and coupled spin-valley degrees of freedom, which are important for the potential application of valleytronics/spintronics based on monolayer semiconductors.

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Authors

  • Aaron Jones

    University of Washington

  • Hongyi Yu

    University of Hong Kong

  • Nirmal Ghimire

    Oak Ridge National Laboratory, The University of Tennessee/Oak Ridge National Laboratory, Department of Physics and Astronomy, University of Tennessee

  • Bo Zhao

    University of Washington

  • Sanfeng Wu

    Department of physics, University of Washington, University of Washington, Department of Physics, University of Washington

  • Grant Aivazian

    University of Washington

  • Jason Ross

    University of Washington

  • Guibin Liu

    University of Hong Kong

  • Jiaqiang Yan

    University of Tennessee, Oak Ridge National Laboratory, Univeristy of Tenessee, Knoxville, Oak Ridge National Laboratory

  • David Mandrus

    University of Tennessee, Dept. Materials Science and Engineering, The University of Tennessee and Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge National Laboratory, The University of Tennessee/Oak Ridge National Laboratory, Materials Science and Engineering, University of Tennessee

  • Wang Yao

    University of Hong Kong

  • Di Xiao

    Carnegie Mellon University

  • Xiaodong Xu

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