Temperature dependence of optical properties of monolayer WS2 by spectroscopic ellipsometry
- Authors
- Hoang Tung Nguyen; Kim, Tae Jung; Park, Han Gyeol; Van Long Le; Nguyen, Xuan Au; Koo, Dohyoung; Lee, Chul-Ho; Cuong, Do Duc; Hong, Soon Cheol; Kim, Young Dong
- Issue Date
- 1-5월-2020
- Publisher
- ELSEVIER
- Keywords
- Spectroscopic ellipsometry; Monolayer tungsten disulphide (WS2); Dielectric function; Exciton; Critical point; Temperature dependence
- Citation
- APPLIED SURFACE SCIENCE, v.511
- Indexed
- SCIE
SCOPUS
- Journal Title
- APPLIED SURFACE SCIENCE
- Volume
- 511
- URI
- https://scholar.korea.ac.kr/handle/2021.sw.korea/56054
- DOI
- 10.1016/j.apsusc.2020.145503
- ISSN
- 0169-4332
- Abstract
- The complex dielectric function epsilon = epsilon(1) + i epsilon(2) 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.
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Collections - Graduate School > KU-KIST Graduate School of Converging Science and Technology > 1. Journal Articles
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