Neutral and charged dark excitons in monolayer WS2

Low temperature and polarization resolved magneto-photoluminescence experiments are used to investigate the properties of dark excitons and dark trions in a monolayer of WS2 encapsulated in hexagonal BN (hBN). We find that this system is an n-type doped semiconductor and that dark trions dominate th...

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Bibliographic Details
Published in:Nanoscale 2020-09, Vol.12 (35), p.18153-18159
Main Authors: Zinkiewicz, M, Slobodeniuk, A O, Kazimierczuk, T, Kapuściński, P, Oreszczuk, K, Grzeszczyk, M, Bartos, M, Nogajewski, K, Watanabe, K, Taniguchi, T, Faugeras, C, Kossacki, P, Potemski, M, Babiński, A, Molas, M R
Format: Article
Language:English
Subjects:
Decay rate
Emission analysis
Excitons
Low temperature
Magnetic properties
Monolayers
N-type semiconductors
Photoluminescence
Polarization
Trions
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Summary:Low temperature and polarization resolved magneto-photoluminescence experiments are used to investigate the properties of dark excitons and dark trions in a monolayer of WS2 encapsulated in hexagonal BN (hBN). We find that this system is an n-type doped semiconductor and that dark trions dominate the emission spectrum. In line with previous studies on WSe2, we identify the Coulomb exchange interaction coupled neutral dark and grey excitons through their polarization properties, while an analogous effect is not observed for dark trions. Applying the magnetic field in both perpendicular and parallel configurations with respect to the monolayer plane, we determine the g-factor of dark trions to be g ∼ −8.6. Their decay rate is close to 0.5 ns, more than 2 orders of magnitude longer than that of bright excitons.
ISSN:2040-3364
2040-3372
DOI:10.1039/d0nr04243a