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Interlayer Excitonic Spectra of Vertically Stacked MoSe2/WSe2 Heterobilayers
physica status solidi (b), Volume: 258, Issue: 7
Swansea University Author:
Roland Gillen
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DOI (Published version): 10.1002/pssb.202000614
Abstract
The optical spectra of vertically stacked MoSe 2 /WSe 2 heterostructures containadditional “interlayer” excitonic peaks that are absent in the individualmonolayer materials and exhibit a significant spatial charge separation in out-of-plane direction. A many-body perturbation theory approach is used...
| Published in: | physica status solidi (b) |
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| ISSN: | 0370-1972 1521-3951 |
| Published: |
Wiley
2021
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| Online Access: |
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| URI: | https://cronfa.swan.ac.uk/Record/cronfa66654 |
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| Abstract: |
The optical spectra of vertically stacked MoSe 2 /WSe 2 heterostructures containadditional “interlayer” excitonic peaks that are absent in the individualmonolayer materials and exhibit a significant spatial charge separation in out-of-plane direction. A many-body perturbation theory approach is used tosimulate the excitonic spectra of MoSe2 /WSe 2 heterobilayers with threestacking orders, considering both momentum-direct and momentum-indirectexcitons. The small oscillator strengths and the optical responses of theinterlayer excitons are significantly stacking-dependent and give rise to highradiative lifetimes in the range of 5–200 ns at low temperature for the “bright”interlayer excitons. Solving the finite-momentum Bethe–Salpeter Equation(BSE), the lowest energy excitation is predicted to be an exciton over thefundamental indirect band gap, with a binding energy of 220 meV. However,in agreement with recent magneto-optics experiments and previous theo-retical studies, the simulations of the effective excitonicg-factors suggest thatthe low energy momentum-indirect excitons are not experimentally observed.The existence of “interlayer”C excitons with significant exciton bindingenergies and optical oscillator strengths is further revealed, which are anal-ogous to the prominent band nesting excitons in mono- and few-layertransition-metal dichalcogenides.RESEARCH ARTICLEwww.pss-b.comPhys. Status Solidi B 2021, 258, 2000614 2000614 (1 of 19) © 2021 The Authors. physica status solidi (b) basic solid state physicspublished by Wiley-VCH GmbH |
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| Keywords: |
Bethe–Salpeter calculations; exciton g-factors; exciton lifetimes; interlayer excitons; transition-metal dichalcogenide heterostructures |
| College: |
Faculty of Science and Engineering |
| Funders: |
North-German Supercomputing Alliance. Grant Number: bep00047
Regional Computing Center Erlangen |
| Issue: |
7 |