Enhanced resonant Raman spectrum of multilayer WS<sub>2</sub> with thin film plasmonic cavity

ORAL

Abstract

Interactions of tightly bound electron-hole pairs (excitons) and the lattice vibration modes (photon) in two-dimension (2D) transition metal dichalcogenide (TMD) crystal is a subject of considerable current interest. Here, we report investigations of exciton resonance Raman spectroscopy assisted by plasmonic thin film cavity from single monolayer to tens of monolayers in WS2. Without the plasmonic cavity and under A exciton resonant excitation condition, the Raman response indeed shows strong enhancement relative to the no-resonance condition, as reported by others previously [1]. With plasmonic cavity, the Raman signal is enhanced further as anticipated [2]. However, we find the enhancement factor show dramatic dependence on the TMD layer thickness with an optimal thickness in the range of few nanometer. More specifically, we find that at this range of thickness, the Raman enhancement is more than 2 orders of magnitude higher than that for the monolayer case. Possible mechanisms will be discussed.

[1] Xin Zhang,et al. Chem. Soc. Rev., 44, 2757 (2015)
[2] Yexin Zhang, et al. Nano Lett. 19, 6284−6291 (2019)

*We acknowledge funding from the AOARD FA-2386-18-1-4097 in US and MOST 108-2119-M-007-008 in Taiwan.

–

Presenters

  • Chun Yuan Wang

    • Physics, University of Texas at Austin
    • University of Texas at Austin

Authors

  • Chun Yuan Wang

    • Physics, University of Texas at Austin
    • University of Texas at Austin

  • Meng Hsien Lin

    • 2. Meta-SERS co. ltd, Taiwan

  • Hung Ying Chen

    • 2. Meta-SERS co. ltd, Taiwan

  • Jiamin Quan

    • Physics, University of Texas at Austin
    • Department of Physics, The University of Texas at Austin
    • University of Texas at Austin
    • Department of Physics, Complex Quantum Systems, and Texas Materials Institutes, University of Texas at Austin

  • Junho Choi

    • Physics, University of Texas at Austin
    • University of Texas at Austin
    • Department of Physics, Complex Quantum Systems, and Texas Materials Institutes, University of Texas at Austin

  • Xiaoqin (Elaine) Li

    • Physics, University of Texas at Austin
    • Department of Physics, The University of Texas at Austin
    • Department of Physics, University of Texas at Austin
    • University of Texas at Austin
    • Department of Physics, Complex Quantum Systems, and Texas Materials Institutes, University of Texas at Austin

  • Shangjr Gwo

    • Physics, National Tsing Hua University

  • Chih-Kang Shih

    • University of Texas at Austin
    • Physics, University of Texas at Austin
    • Department of Physics, The University of Texas at Austin