Excitonic linewidth and coherence lifetime in monolayer transition metal dichalcogenides.
Nat Commun
; 7: 13279, 2016 11 07.
Article
in En
| MEDLINE
| ID: mdl-27819288
ABSTRACT
Atomically thin transition metal dichalcogenides are direct-gap semiconductors with strong light-matter and Coulomb interactions. The latter accounts for tightly bound excitons, which dominate their optical properties. Besides the optically accessible bright excitons, these systems exhibit a variety of dark excitonic states. They are not visible in the optical spectra, but can strongly influence the coherence lifetime and the linewidth of the emission from bright exciton states. Here, we investigate the microscopic origin of the excitonic coherence lifetime in two representative materials (WS2 and MoSe2) through a study combining microscopic theory with spectroscopic measurements. We show that the excitonic coherence lifetime is determined by phonon-induced intravalley scattering and intervalley scattering into dark excitonic states. In particular, in WS2, we identify exciton relaxation processes involving phonon emission into lower-lying dark states that are operative at all temperatures.
Full text:
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Collection:
01-internacional
Database:
MEDLINE
Language:
En
Journal:
Nat Commun
Year:
2016
Document type:
Article