Excitonic linewidth and coherence lifetime in monolayer transition metal dichalcogenides
Journal article, 2016

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.

Author

M. Selig

Technische Universität Berlin

Gunnar Berghäuser

Technische Universität Berlin

A. Raja

Columbia University in the City of New York

Stanford University

P. Nagler

University of Regensburg

C. Schuller

University of Regensburg

T. F. Heinz

Stanford University

Columbia University in the City of New York

T. Korn

University of Regensburg

A. Chernikov

University of Regensburg

Columbia University in the City of New York

Ermin Malic

Chalmers, Physics, Condensed Matter Theory

A. Knorr

Technische Universität Berlin

Nature Communications

2041-1723 (ISSN)

Vol. 7 Article no 13279- 13279

Graphene-Based Revolutions in ICT And Beyond (Graphene Flagship)

European Commission (FP7), 2013-10-01 -- 2016-03-31.

Subject Categories

Atom and Molecular Physics and Optics

DOI

10.1038/ncomms13279

More information

Latest update

6/25/2018