Excitonic linewidth and coherence lifetime in monolayer transition metal dichalcogenides
Artikel i vetenskaplig tidskrift, 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.

Författare

M. Selig

Technische Universität Berlin

Gunnar Berghäuser

Technische Universität Berlin

A. Raja

Stanford University

Columbia University in the City of New York

P. Nagler

Universität Regensburg

C. Schuller

Universität Regensburg

T. F. Heinz

Columbia University in the City of New York

Stanford Linear Accelerator Center

Stanford University

T. Korn

Universität Regensburg

A. Chernikov

Columbia University in the City of New York

Universität Regensburg

Ermin Malic

Chalmers, Fysik, Kondenserade materiens teori

A. Knorr

Technische Universität Berlin

Nature Communications

2041-1723 (ISSN)

Vol. 7 Article no 13279- 13279

Ämneskategorier

Atom- och molekylfysik och optik

DOI

10.1038/ncomms13279