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Excitonic linewidth and coherence lifetime in monolayer transition metal dichalcogenides

M. Selig ; Gunnar Berghäuser ; A. Raja ; P. Nagler ; C. Schuller ; T. F. Heinz ; T. Korn ; A. Chernikov ; Ermin Malic (Institutionen för fysik, Kondenserade materiens teori (Chalmers)) ; A. Knorr
Nature Communications (2041-1723). Vol. 7 (2016), p. Article no 13279.
[Artikel, refereegranskad vetenskaplig]

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.



Denna post skapades 2016-11-30. Senast ändrad 2017-09-06.
CPL Pubid: 245740

 

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Institutioner (Chalmers)

Institutionen för fysik, Kondenserade materiens teori (Chalmers)

Ämnesområden

Atom- och molekylfysik och optik

Chalmers infrastruktur

 


Projekt

Denna publikation är ett resultat av följande projekt:


Graphene-Based Revolutions in ICT And Beyond (GRAPHENE) (EC/FP7/604391)