The origin of single photon emission in 2D WSe<sub>2</sub>

ORAL

Abstract

Several experimental groups have shown that defect structures in 2D WSe2 result in single photon emission (SPE). However, the origin of SPE is still unknown. We present a first principles study of the nature and optical properties of point defects in 2D WSe2, together with scanning tunneling microscopy (STM) and scanning transmission electron microscopy images. We predict that O2 can dissociate easily at Se vacancies, resulting in O-passivated Se vacancies (OSe) and O interstitials (Oins), which give STM images in good agreement with experiment. Our GW-Bethe-Salpeter-equation calculations show that Oins defects give exciton peaks ~50-100 meV below the free exciton peak, in good agreement with the localized excitons observed in independent SPE experiments. No other point defect (OSe, Se vacancies, W vacancies, and SeW antisite defects) gives excitons in the same energy range. We conclude that the Oins defect is a source for the SPE previously observed in 2D WSe2.

*We acknowledge grant NRF-NRFF2013-07 from the National Research Foundation (NRF), Singapore; ASTAR Pharos grant R-144-000-359-305; and support from the Singapore NRF, Prime Minister’s Office, under its medium-sized centre program. SJP and PKG acknowledge MOE grant number R-144-000-389-114.

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Presenters

  • Yifeng Chen

    • Centre for Advanced 2D Materials, National University of Singapore

Authors

  • Yu Jie Zheng

    • Department of Physics, National University of Singapore

  • Yifeng Chen

    • Centre for Advanced 2D Materials, National University of Singapore

  • Yu Li Huang

    • Institute of Materials Research & Engineering (IMRE), A*STAR (Agency for Science, Technology and Research)

  • Pranjal Kumar Gogoi

    • Department of Physics, National University of Singapore

  • Ming-Yang Li

    • Physical Sciences and Engineering, King Abdullah University of Science and Technology
    • Corporate Research and Chief Technology Office, Taiwan Semiconductor Manufacturing Company (TSMC)

  • Lain-Jong Li

    • Physical Sciences and Engineering, King Abdullah University of Science and Technology
    • Physical Sciences and Engineering Division, King Abdullah University of Science and Technology

  • Paolo E Trevisanutto

    • Centre for Advanced 2D Materials, National University of Singapore

  • Qixing Wang

    • Department of Physics, National University of Singapore

  • Stephen J Pennycook

    • Department of Materials Science & Engineering, National University of Singapore

  • Andrew Thye Shen Wee

    • Department of Physics, National University of Singapore

  • Su Ying Quek

    • National University of Singapore
    • Centre for Advanced 2D Materials, National University of Singapore