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Title: Excitonic linewidth and coherence lifetime in monolayer transition metal dichalcogenides

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. We investigate the microscopic origin of the excitonic coherence lifetime in two representative materials (WS 2 and MoSe 2) through a study combining microscopic theory with spectroscopic measurements. We also show that the excitonic coherence lifetime is determined by phonon-induced intravalley scattering and intervalley scattering into dark excitonic states. Particularly, we identify exciton relaxation processes involving phonon emission into lower-lying dark states that are operative at all temperatures, in WS 2.
Authors:
 [1] ;  [1] ;  [2] ;  [3] ;  [3] ;  [4] ;  [3] ;  [5] ;  [6] ;  [1]
  1. Technical Univ. of Berlin (Germany). Inst. for Theoretical Physics
  2. Columbia Univ., New York, NY (United States). Dept. of Chemistry; Stanford Univ., CA (United States). Dept. of Applied Physics
  3. Univ. of Regensburg (Germany). Inst. for Experimental and Applied Physics
  4. Stanford Univ., CA (United States). Dept. of Applied Physics; SLAC National Accelerator Lab., Menlo Park, CA (United States); Columbia Univ., New York, NY (United States). Dept. of Physics and Electrical Engineering
  5. Univ. of Regensburg (Germany). Inst. for Experimental and Applied Physics; Columbia Univ., New York, NY (United States). Dept. of Physics and Electrical Engineering
  6. Chalmers Univ. of Technology, Gothenburg (Sweden). Dept. of Physics
Publication Date:
Grant/Contract Number:
AC02-76SF00515
Type:
Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 7; Journal ID: ISSN 2041-1723
Publisher:
Nature Publishing Group
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; electronic properties and materials; optical physics; two-dimensional materials
OSTI Identifier:
1348911

Selig, Malte, Berghäuser, Gunnar, Raja, Archana, Nagler, Philipp, Schüller, Christian, Heinz, Tony F., Korn, Tobias, Chernikov, Alexey, Malic, Ermin, and Knorr, Andreas. Excitonic linewidth and coherence lifetime in monolayer transition metal dichalcogenides. United States: N. p., Web. doi:10.1038/ncomms13279.
Selig, Malte, Berghäuser, Gunnar, Raja, Archana, Nagler, Philipp, Schüller, Christian, Heinz, Tony F., Korn, Tobias, Chernikov, Alexey, Malic, Ermin, & Knorr, Andreas. Excitonic linewidth and coherence lifetime in monolayer transition metal dichalcogenides. United States. doi:10.1038/ncomms13279.
Selig, Malte, Berghäuser, Gunnar, Raja, Archana, Nagler, Philipp, Schüller, Christian, Heinz, Tony F., Korn, Tobias, Chernikov, Alexey, Malic, Ermin, and Knorr, Andreas. 2016. "Excitonic linewidth and coherence lifetime in monolayer transition metal dichalcogenides". United States. doi:10.1038/ncomms13279. https://www.osti.gov/servlets/purl/1348911.
@article{osti_1348911,
title = {Excitonic linewidth and coherence lifetime in monolayer transition metal dichalcogenides},
author = {Selig, Malte and Berghäuser, Gunnar and Raja, Archana and Nagler, Philipp and Schüller, Christian and Heinz, Tony F. and Korn, Tobias and Chernikov, Alexey and Malic, Ermin and Knorr, Andreas},
abstractNote = {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. 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 also show that the excitonic coherence lifetime is determined by phonon-induced intravalley scattering and intervalley scattering into dark excitonic states. Particularly, we identify exciton relaxation processes involving phonon emission into lower-lying dark states that are operative at all temperatures, in WS2.},
doi = {10.1038/ncomms13279},
journal = {Nature Communications},
number = ,
volume = 7,
place = {United States},
year = {2016},
month = {11}
}