Local Optical Properties in CVD-Grown Monolayer WS2 Flakes


Magnozzi M., Pflug T., Ferrera M., Pace S., Ramo L., Olbrich M., ...More

JOURNAL OF PHYSICAL CHEMISTRY C, vol.125, no.29, pp.16059-16065, 2021 (Journal Indexed in SCI) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 125 Issue: 29
  • Publication Date: 2021
  • Doi Number: 10.1021/acs.jpcc.1c04287
  • Title of Journal : JOURNAL OF PHYSICAL CHEMISTRY C
  • Page Numbers: pp.16059-16065

Abstract

Excitons dominate the light absorption and re-emission spectra of monolayer transition-metal dichalcogenides (TMD). Microscopic investigations of the excitonic response in TMD almost invariably extract information from the radiative recombination step, which only constitutes one part of the picture. Here, by exploiting imaging spectroscopic ellipsometry (ISE), we investigate the spatial dependence of the dielectric function of chemical vapor deposition (CVD)-grown WS2 flakes with a microscopic lateral resolution, thus providing information about the spatially varying, exciton-induced light absorption in the monolayer WS2 Comparing the ISE results with imaging photoluminescence spectroscopy data, the presence of several correlated features was observed, along with the unexpected existence of a few uncorrelated characteristics. The latter demonstrates that the exciton-induced absorption and emission features are not always proportional at the microscopic scale. Microstructural modulations across the flakes, having a different influence on the absorption and re-emission of light, are deemed responsible for the effect.