Coherent quantum dynamics of excitons in monolayer transition metal dichalcogenides
Paper in proceeding, 2016
Transition metal dichalcogenides (TMDs) have garnered considerable interest in recent years owing to their layer thickness-dependent optoelectronic properties. In monolayer TMDs, the large carrier effective masses, strong quantum confinement, and reduced dielectric screening lead to pronounced exciton resonances with remarkably large binding energies and coupled spin and valley degrees of freedom (valley excitons). Coherent control of valley excitons for atomically thin optoelectronics and valleytronics requires understanding and quantifying sources of exciton decoherence. In this work, we reveal how exciton-exciton and exciton-phonon scattering influence the coherent quantum dynamics of valley excitons in monolayer TMDs, specifically tungsten diselenide (WSe2), using two-dimensional coherent spectroscopy. Excitation-density and temperature dependent measurements of the homogeneous linewidth (inversely proportional to the optical coherence time) reveal that exciton-exciton and exciton-phonon interactions are significantly stronger compared to quasi-2D quantum wells and 3D bulk materials. The residual homogeneous linewidth extrapolated to zero excitation density and temperature is 1:6 meV (equivalent to a coherence time of 0.4 ps), which is limited only by the population recombination lifetime in this sample. (c) (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only
spin
photoluminescence
Exciton
wse2
lifetimes
semiconductor
Multi-Dimensional Coherent Spectroscopy
crystals
mono layer
Homogeneous Linewidth
valley polarization
Transition Metal Dichalcogenides
molybdenum-disulfide
mos2
Author
G. Moody
National Institute of Standards and Technology (NIST)
The University of Texas at Austin
K. Hao
The University of Texas at Austin
C. K. Dass
The University of Texas at Austin
A. Singh
The University of Texas at Austin
L. X. Xu
The University of Texas at Austin
K. Tran
The University of Texas at Austin
C. H. Chen
Feng Chia University
M. Y. Li
King Abdullah University of Science and Technology (KAUST)
L. J. Li
King Abdullah University of Science and Technology (KAUST)
G. Clark
University of Washington
Gunnar Berghäuser
Technische Universität Berlin
Ermin Malic
Chalmers, Physics, Condensed Matter Theory
A. Knorr
Technische Universität Berlin
X. D. Xu
University of Washington
X. Q. Li
The University of Texas at Austin
Proceedings of SPIE - The International Society for Optical Engineering
0277786X (ISSN) 1996756X (eISSN)
Vol. 9746 97461T978-1-62841-981-8 (ISBN)
Subject Categories
Atom and Molecular Physics and Optics
Electrical Engineering, Electronic Engineering, Information Engineering
DOI
10.1117/12.2209203
ISBN
978-1-62841-981-8