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Title: Observation of long-lived interlayer excitons in monolayer MoSe2–WSe2 heterostructures

Van der Waals bound heterostructures constructed with two-dimensional materials, such as graphene, boron nitride and transition metal dichalcogenides, have sparked wide interest in both device physics and technologies at the two-dimensional limit. One highly coveted heterostructure is that of differing monolayer transition metal dichalcogenides with type-II band alignment, with bound electrons and holes localized in individual monolayers, that is, interlayer excitons. Here, we report the observation of interlayer excitons in monolayer MoSe2–WSe2 heterostructures by photoluminescence and photoluminescence excitation spectroscopy. The energy and luminescence intensity are highly tunable by an applied vertical gate voltage. Moreover, we measure an interlayer exciton lifetime of ~1.8 ns, an order of magnitude longer than intralayer excitons in monolayers. Ultimately, our work demonstrates optical pumping of interlayer electric polarization, which may provoke further exploration of interlayer exciton condensation, as well as new applications in two-dimensional lasers, light-emitting diodes and photovoltaic devices.
Authors:
 [1] ;  [1] ;  [1] ;  [2] ;  [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7]
  1. Univ. of Washington, Seattle, WA (United States). Dept. of Physics
  2. Univ. of Washington, Seattle, WA (United States). Dept. of Materials Science and Engineering
  3. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Physics and Astronomy; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science & Technology Division
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science & Technology Division; Univ. of Tennessee, Knoxville, TN (United States). Dept. of Materials Science and Engineering
  5. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Physics and Astronomy; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science & Technology Division; Univ. of Tennessee, Knoxville, TN (United States). Dept. of Materials Science and Engineering
  6. Univ. of Hong Kong (China). Dept. of Physics and Center of Theoretical and Computational Physics
  7. Univ. of Washington, Seattle, WA (United States). Dept. of Physics; Univ. of Washington, Seattle, WA (United States). Dept. of Materials Science and Engineering
Publication Date:
OSTI Identifier:
1265431
Grant/Contract Number:
AC05-00OR22725; SC0008145; HKU705513P; HKU8/CRF/11G; DGE-0718124
Type:
Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 6; Journal ID: ISSN 2041-1723
Publisher:
Nature Publishing Group
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF); Research Grant Council of Hong Kong
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE