Robustness of Momentum-Indirect Interlayer Excitons in MoS2/WSe2 Heterostructure against Charge Carrier Doping

Khestanova E, Ivanova T, Gillen R, D'Elia A, Lacey ONG, Wysocki L, Grueneis A, Kravtsov V, Strupinski W, Maultzsch J, Kandyba V, Cattelan M, Barinov A, Avila J, Dudin P, Senkovskiy BV (2022)

Publication Type: Journal article

Publication year: 2022

Journal

ACS Photonics American Chemical Society

DOI: 10.1021/acsphotonics.2c01930

Abstract

Monolayer transition-metal dichalcogenide (TMD) semiconductors exhibit strong excitonic effects and hold promise for optical and optoelectronic applications. Yet, electron doping of TMDs leads to the conversion of neutral excitons into negative trions, which recombine predominantly nonradiatively at room temperature. As a result, the photoluminescence (PL) intensity is quenched. Here we study the optical and electronic properties of a MoS2/WSe2 heterostructure as a function of chemical doping by Cs atoms performed under ultrahigh vacuum conditions. By PL measurements, we identify two interlayer excitons and assign them to the momentum-indirect Q-Γ and K-Γ transitions. The energies of these excitons are in very good agreement with ab initio calculations. We find that the Q-Γ interlayer exciton is robust to the electron doping and is present at room temperature even at a high charge carrier concentration (∼1013 cm-2). Submicrometer angle-resolved photoemission spectroscopy (μ-ARPES) reveals a charge transfer from deposited Cs adatoms to both the upper MoS2 and the lower WSe2 monolayers without changing the band alignment. This leads to a small (∼10 meV) energy shift of interlayer excitons. Robustness of the momentum-indirect interlayer exciton to charge doping opens up an opportunity for using TMD heterostructures in light-emitting devices that can work at room temperature at high densities of charge carriers.

Authors with CRIS profile

Roland Gillen Lehrstuhl für Experimentalphysik Janina Maultzsch Lehrstuhl für Experimentalphysik

Involved external institutions

Universität zu Köln DE Germany (DE) ITMO University / Национальный исследовательский университет ИТМО RU Russian Federation (RU) Warsaw University of Technology / Politechnika Warszawska PL Poland (PL) Elettra Sincrotrone Trieste S.C.p.A. IT Italy (IT) École Polytechnique - Université Paris-Saclay FR France (FR) Autonomous University of Barcelona (UAB) / Universitat Autònoma de Barcelona ES Spain (ES)

How to cite

APA:

Khestanova, E., Ivanova, T., Gillen, R., D'Elia, A., Lacey, O.N.G., Wysocki, L.,... Senkovskiy, B.V. (2022). Robustness of Momentum-Indirect Interlayer Excitons in MoS2/WSe2 Heterostructure against Charge Carrier Doping. ACS Photonics. https://doi.org/10.1021/acsphotonics.2c01930

MLA:

Khestanova, Ekaterina, et al. "Robustness of Momentum-Indirect Interlayer Excitons in MoS2/WSe2 Heterostructure against Charge Carrier Doping." ACS Photonics (2022).

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