Temperature dependence of optical properties of monolayer WS2 by spectroscopic ellipsometry

Hoang Tung Nguyen, Tae Jung Kim, Han Gyeol Park, Van Long Le, Xuan Au Nguyen, Dohyoung Koo, Chul Ho Lee, Do Duc Cuong, Soon Cheol Hong, Young Dong Kim

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)


The complex dielectric function ɛ = ɛ1 + iɛ2 of monolayer tungsten disulfide (WS2) is investigated for the energy range from 1.5 to 6.0 eV and temperatures from 41 to 300 K. Measurements were performed under ultra-high vacuum conditions to avoid degradation and overlayer contamination. Fourteen critical-point (CP) energies were observed and their origins in Brillouin-zone were identified by band structure calculations. At low temperature the A and B excitonic peaks split into four CPs, which is understood as the neutral and charged exciton states of monolayer WS2. At low temperatures the CP energies show blue shifts with enhanced structure due to the reduction of electron-phonon interaction. The temperature dependence of these data was obtained by a phenomenological expression with Bose-Einstein statistical factor.

Original languageEnglish
Article number145503
JournalApplied Surface Science
Publication statusPublished - 2020 May 1


  • Critical point
  • Dielectric function
  • Exciton
  • Monolayer tungsten disulphide (WS)
  • Spectroscopic ellipsometry
  • Temperature dependence

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics
  • Physics and Astronomy(all)
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films


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