Optical signature of symmetry variations and spin-valley coupling in atomically thin tungsten dichalcogenides
University of Hong Kong · Beijing Institute of Technology · +3 more institutions
Abstract
We report systematic optical studies of WS2 and WSe2 monolayers and multilayers. The efficiency of second harmonic generation shows a dramatic even-odd oscillation with the number of layers, consistent with the presence (absence) of inversion symmetry in even-layer (odd-layer). Photoluminescence (PL) measurements show the crossover from an indirect band gap semiconductor at multilayers to a direct-gap one at monolayers. A hot luminescence peak (B) is observed at ~0.4 eV above the prominent band edge peak (A) in all samples. The magnitude of A-B splitting is independent of the number of layers and coincides with the spin-valley coupling strength in monolayers. Ab initio calculations show that this thickness…
Citation impact
- FWCI
- 33.60
- Percentile
- 100%
- References
- 27
Authors
11- HZHualing ZengCorresponding
University of Hong Kong
- GLGui-Bin Liu
University of Hong Kong, Beijing Institute of Technology
- JDJunfeng Dai
Southern University of Science and Technology, University of Hong Kong
- YYYajun Yan
University of Science and Technology of China, Hefei National Center for Physical Sciences at Nanoscale
- BZBairen Zhu
University of Hong Kong
Topics & keywords
- Photoluminescence
- Stacking
- Point reflection
- Coupling (piping)
- Ab initio quantum chemistry methods
- Semiconductor
- Tungsten
- Band gap