Intrinsic homogeneous linewidth and broadening mechanisms of excitons in monolayer transition metal dichalcogenides
Journal article, 2015
The band-edge optical response of transition metal dichalcogenides, an emerging class of atomically thin semiconductors, is dominated by tightly bound excitons localized at the corners of the Brillouin zone (valley excitons). A fundamental yet unknown property of valley excitons in these materials is the intrinsic homogeneous linewidth, which reflects irreversible quantum dissipation arising from system (exciton) and bath (vacuum and other quasiparticles) interactions and determines the timescale during which excitons can be coherently manipulated. Here we use optical two-dimensional Fourier transform spectroscopy to measure the exciton homogeneous linewidth in monolayer tungsten diselenide (WSe 2). The homogeneous linewidth is found to be nearly two orders of magnitude narrower than the inhomogeneous width at low temperatures. We evaluate quantitatively the role of exciton-exciton and exciton-phonon interactions and population relaxation as linewidth broadening mechanisms. The key insights reported here - strong many-body effects and intrinsically rapid radiative recombination - are expected to be ubiquitous in atomically thin semiconductors.
Author
G. Moody
University of Texas
National Institute of Standards and Technology (NIST)
C. Kavir Dass
University of Texas
K. Hao
University of Texas
C. H. Chen
Feng Chia University
L. J. Li
King Abdullah University of Science and Technology (KAUST)
A. Singh
University of Texas
K. Tran
University of Texas
G. Clark
University of Washington
X. Xu
University of Washington
Gunnar Berghäuser
Technische Universität Berlin
Ermin Malic
Chalmers, Applied Physics, Condensed Matter Theory
A. Knorr
Technische Universität Berlin
X. Li
University of Texas
Nature Communications
2041-1723 (ISSN) 20411723 (eISSN)
Vol. 6 Art. no. 8315- 8315Graphene-Based Revolutions in ICT And Beyond (Graphene Flagship)
European Commission (EC) (EC/FP7/604391), 2013-10-01 -- 2016-03-31.
Subject Categories (SSIF 2011)
Physical Sciences
Metallurgy and Metallic Materials
DOI
10.1038/ncomms9315
PubMed
26382305