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Emergence of highly linearly polarized interlayer exciton emission in MoSe₂/WSe₂ heterobilayers with transfer-induced layer corrugation

Lookup NU author(s): Dr Aleksey KozikovORCiD

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Abstract

The availability of accessible fabrication methods based on deterministic transfer of atomically thin crystals has been essential for the rapid expansion of research into van der Waals heterostructures. An inherent issue of these techniques is the deformation of the polymer carrier film during the transfer, which can lead to highly nonuniform strain induced in the transferred two-dimensional material. Here, using a combination of optical spectroscopy, atomic force, and Kelvin probe force microscopy, we show that the presence of nanometer scale wrinkles formed due to transfer-induced stress relaxation can lead to strong changes in the optical properties of MoSe2/WSe2 heterostructures and the emergence of linearly polarized interlayer exciton photoluminescence. We attribute these changes to local breaking of crystal symmetry in the nanowrinkles, which act as efficient accumulation centers for interlayer excitons due to the strain-induced interlayer band gap reduction. Surface potential images of the rippled heterobilayer samples acquired using Kelvin probe force microscopy reveal variations of the local work function consistent with strain-induced band gap modulation, while the potential offset observed at the ridges of the wrinkles shows a clear correlation with the value of the tensile strain estimated from the wrinkle geometry. Our findings highlight the important role of the residual strain in defining optical properties of van der Waals heterostructures and suggest effective approaches for interlayer exciton manipulation by local strain engineering.

Publication metadata

Author(s): Alexeev EM, Mullin N, Ares P, Nevison-Andrews H, Skrypka OV, Godde T, Kozikov A, Hague L, Wang Y, Novoselov KS, Fumagalli L, Hobbs JK, Tartakovskii AI

Publication type: Article

Publication status: Published

Journal: ACS Nano

Year: 2020

Volume: 14

Issue: 9

Pages: 11110–11119

Print publication date: 22/09/2020

Online publication date: 17/08/2020

Acceptance date: 17/08/2020

ISSN (print): 1936-0851

ISSN (electronic): 1936-086X

Publisher: American Chemical Society

URL: https://doi.org/10.1021/acsnano.0c01146

DOI: 10.1021/acsnano.0c01146

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