https://doi.org/10.1140/epjp/s13360-022-03537-2
Regular Article
Band valley flattening and exciton appearance/disappearance under isotropic strain in monolayer WS2
1
Faculty of Physics, Hanoi Pedagogical University 2, Hanoi, Vietnam
2
Faculty of Fundamental Sciences, Hanoi University of Industry, Hanoi, Vietnam
3
Institute of Sustainability Science, VNU Vietnam Japan University, Hanoi, Vietnam
4
Department of Application and Development of Technology, Vietnam Academy of Science and Technology, Hanoi, Vietnam
5
Department of Precision Engineering, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, 565-0871, Suita, Osaka, Japan
6
Hoa Binh University, Hanoi, Vietnam
a
tranquanghuy@hpu2.edu.vn
f
divan@prec.eng.osaka-u.ac.jp
Received:
7
July
2022
Accepted:
24
November
2022
Published online:
7
December
2022
Mechanism of exciton appearance and disappearance under isotropic strain in monolayer WS2 is investigated using the non-local van der Waals density functionals theory with taking into account the spin–orbit coupling (SOC). The essential effects such as vertical shift (the shift in the binding energy scale) of the d and p partial orbitals of the W and S atoms, respectively, and the flattening of band valleys caused by strain are explored. The exciton appearance and disappearance in the isotropic strained WS2 are discussed. Thanks to the spin splitting by SOC effect, light and dark excitons are visually shown. Under strain, the flattening of the band valleys may lead to the disappearance of excitons, causing the direct-to-indirect transition of the band gap. Furthermore, the vertical shift of electron orbitals at band edges can result in a notable reduction in the band gap. These findings can open a possible path to manipulate excitons using strain scheme.
© The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2022. Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
