Raman scattering excitation in monolayers of semiconducting transition metal dichalcogenides
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Date
2024-01-10
Authors
Bartoš, Miroslav
Zinkiewitz, Malgorzata
Grzeszczyk, Magdalena
Kazimierczuk, Tomasz
Nogajewski, Karol
Pacuski, Wojciech
Watanabe, Kenji
Taniguchi, Takashi
Wysmołek, Andrzej
Kossacki, Piotr
ORCID
0000-0002-5923-0260Advisor
Referee
Mark
Journal Title
Journal ISSN
Volume Title
Publisher
NATURE PORTFOLIO
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Abstract
Raman scattering excitation (RSE) is an experimental technique in which the spectrum is made up by sweeping the excitation energy when the detection energy is fixed. We study the low-temperature (T = 5 K) RSE spectra measured on four high quality monolayers (ML) of semiconducting transition metal dichalcogenides (S-TMDs), i.e. MoS2, MoSe2, WS2, and WSe2, encapsulated in hexagonal BN. The outgoing resonant conditions of Raman scattering reveal an extraordinary intensity enhancement of the phonon modes, which results in extremely rich RSE spectra. The obtained spectra are composed not only of Raman-active peaks, i.e. in-plane E ' and out-of-plane A(1)', but the appearance of 1st, 2nd, and higher-order phonon modes is recognized. The intensity profiles of the A(1)' modes in the investigated MLs resemble the emissions due to neutral excitons measured in the corresponding PL spectra for the outgoing type of resonant Raman scattering conditions. Furthermore, for the WSe2 ML, the A(1)' mode was observed when the incoming light was in resonance with the neutral exciton line. The strength of the exciton-phonon coupling (EPC) in S-TMD MLs strongly depends on the type of their ground excitonic state, i.e. bright or dark, resulting in different shapes of the RSE spectra. Our results demonstrate that RSE spectroscopy is a powerful technique for studying EPC in S-TMD MLs.
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Citation
npj 2D Materials and Applications. 2024, vol. 8, issue 1, 7 p.
https://www.nature.com/articles/s41699-023-00438-5
https://www.nature.com/articles/s41699-023-00438-5
Document type
Peer-reviewed
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en