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Nat Commun. 2015 Feb 24;6:6242. doi: 10.1038/ncomms7242.

Observation of long-lived interlayer excitons in monolayer MoSe2-WSe2 heterostructures.

Author information

1
Department of Physics, University of Washington, Seattle, Washington 98195, USA.
2
Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195, USA.
3
1] Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA [2] Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
4
1] Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA [2] Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA.
5
1] Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA [2] Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA [3] Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA.
6
Department of Physics and Center of Theoretical and Computational Physics, University of Hong Kong, Hong Kong, China.
7
1] Department of Physics, University of Washington, Seattle, Washington 98195, USA [2] Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195, USA.

Abstract

Van der Waals bound heterostructures constructed with two-dimensional materials, such as graphene, boron nitride and transition metal dichalcogenides, have sparked wide interest in 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. We find that their energy and luminescence intensity are highly tunable by an applied vertical gate voltage. Moreover, we measure an interlayer exciton lifetime of ~1.8‚ÄČns, an order of magnitude longer than intralayer excitons in monolayers. 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.

PMID:
25708612
DOI:
10.1038/ncomms7242

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