Momentum-resolved study of dark excitons in 2D semiconductors by TR-ARPES

ORAL

Abstract

Excitons - quasiparticles formed by coulomb-bounded electron-hole pairs, play a key role in the optical response of 2D semiconductors. In Transition Metal Dichalcogenides – prototypical 2D semiconductors, a complex excitonic landscape exists, including a significant population of spin- or momentum- forbidden dark excitons. While dark excitons are generally invisible to light, they can be directly imaged using time- and angle- resolved photoemission spectroscopy (TR-ARPES) [1,2]. Here, we directly image the wavefunctions of the momentum- and spin-dark excitons and understand the impact of the electron-hole exchange interaction on their size and binding energy.

[1] J. Madéo et al., Directly Visualizing the Momentum-Forbidden Dark Excitons and Their Dynamics in Atomically Thin Semiconductors, Science 370, 1199 (2020).

[2] M. K. L. Man et al., Experimental Measurement of the Intrinsic Excitonic Wave Function, Science Advances 7, eabg0192 (2021).

*This work was supported in part by JSPS Kakenhi grant number 21H01020. Funding was also provided in part by the Femtosecond Spectroscopy Unit of the Okinawa Institute of Science and Technology Graduate University. We thank the OIST engineering support section for their support.

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Presenters

  • Xing Zhu

    • Okinawa Institute of Science & Technology

Authors

  • Xing Zhu

    • Okinawa Institute of Science & Technology

  • David R Bacon

    • Okinawa Institute of Science & Technology

  • Vivek Pareek

    • Okinawa Institute of Science & Technology

  • Julien Madéo

    • Okinawa Institute of Science & Technology
    • Okinawa Institute of Science and Technology

  • Kenji Watanabe

    • National Institute for Materials Science
    • NIMS
    • Research Center for Functional Materials, National Institute for Materials Science
    • Research Center for Electronic and Optical Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
    • Research Center for Functional Materials, National Institute of Material Science, Tsukuba, Japan
    • National Institute of Materials Science
    • Advanced Materials Laboratory, National Institute for Materials Science

  • Takashi Taniguchi

    • National Institute for Materials Science
    • International Center for Materials Nanoarchitectonics, National Institute for Materials Science
    • Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
    • International Center for Materials Nanoarchitectonics, National Institute of Material Science, Tsukuba, Japan
    • Advanced Materials Laboratory, National Institute for Materials Science

  • Michael. K. L. Man

    • Okinawa Institute of Science & Technology
    • Okinawa Institute of Science and Technology

  • Mit H. Naik

    • University of California, Berkeley
    • University of Texas at Austin

  • Keshav M Dani

    • Okinawa Institute of Science & Technology