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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