Nanoscale-resolved spectroscopy of excitons in atomically-thin transition metal dichalcogenides

POSTER

Abstract

Excitons play a dominant role in opto-electronic properties of atomically thin van der Waals semiconductors, such as transition metal dichalcogenides (TMDs). Further, excitons can be engineered by dielectric screening, interlayer hybridization and moiré potentials. These engineering knobs inherently lead to heterogeneous properties at the nanoscale. However, probing the optical response from excitons at the nanoscale is a formidable task. In this talk, we couple a tunable continuous-wave laser to a scattering-type scanning near-field optical microscope (s-SNOM), and measure the near-infrared optical spectra of a MoSe2 monolayer, WSe2 monolayer, MoSe2/WSe2 heterobilayer and WSe2 trilayer at nanoscale. The observed spectra, in all cases, reveal resonances that we attribute to excitonic optical responses and are resolved with 20 nm spatial resolution. Nanoscale-resolved dielectric functions can be extracted quantitatively from s-SNOM spectra. Further, the evolution of both exciton resonance energies and radiation rates in a MoSe2/WSe2 heterobilayer and a WSe2 trilayer relative to their isolated monoayers is investigated. Our work brings opportunities for locally exploring excitons with nanoscale spatial inhomogeneity, such as moiré exciton and exciton polarition.

Presenters

  • Shuai Zhang

    • Department of Physics, Columbia University
    • Columbia Univ
    • Columbia University

Authors

  • Shuai Zhang

    • Department of Physics, Columbia University
    • Columbia Univ
    • Columbia University

  • Baichang Li

    • Department of Mechanical Engineering, Columbia University
    • Columbia University

  • Francesco Ruta

    • Department of Physics, Columbia University
    • Columbia University
    • Columbia Univ

  • Yinming Shao

    • Department of Physics, Columbia University
    • Columbia Univ
    • Columbia University

  • Aaron Sternbach

    • Department of Physics, Columbia University
    • Columbia University
    • Columbia Univ

  • Alexander S McLeod

    • Columbia University
    • Department of Physics, Columbia University
    • Columbia Univ

  • Zhiyuan Sun

    • Columbia University
    • Department of Physics, Columbia University
    • Columbia Univ

  • Lin Xiong

    • Department of Physics, Columbia University
    • Columbia Univ
    • Columbia University

  • Samuel Moore

    • Department of Physics, Columbia University
    • Columbia University

  • Xinyi Xu

    • Columbia University
    • Department of Mechanical Engineering, Columbia University
    • Columbia Univ

  • Wenjing Wu

    • Department of Chemistry, Columbia University
    • Columbia Univ
    • Columbia University

  • Lin Zhou

    • Department of Chemistry, Columbia University

  • Zhiying Wang

    • Department of Mechanical Engineering, Columbia University
    • Columbia Univ

  • Essance Ray

    • Department of Physics, University of Washington

  • Nathan P Wilson

    • Department of Physics, University of Washington
    • University of Washington

  • P James Schuck

    • Department of Mechanical Engineering, Columbia University
    • Columbia University

  • Michal Lipson

    • Department of Electrical Engineering, Columbia University
    • Columbia Univ

  • Xiaodong Xu

    • Physics, University of Washington
    • Department of Physics, University of Washington
    • University of Washington
    • Department of Physics, University of Washington, Seattle
    • University of Washington, Seattle

  • Xiaoyang Zhu

    • Columbia University
    • Chemistry, Columbia university
    • Chemistry, Columbia University
    • Department of Chemistry, Columbia University

  • Michael Fogler

    • University of California, San Diego
    • Department of Physics, University of California San Diego
    • UC San Diego
    • Department of Physics, University of California, San Diego
    • UCSD
    • University of California San Diego

  • James Hone

    • Columbia Univ
    • Columbia University
    • Department of Mechanical Engineering, Columbia University
    • Mechanical Engineering, Columbia University

  • Dmitri Basov

    • Columbia University
    • Department of Physics, Columbia University
    • Physics, Columbia University
    • Columbia Univ