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arXiv · 1703.00806

Defect healing and charge transfer mediated valley polarization in MoS$_2$/MoSe$_2$/MoS$_2$ trilayer van der Waals heterostructures

Alessandro Surrente·Dumitru Dumcenco·Zhuo Yang·Agnieszka Kuc·Yu Jing·Thomas Heine·Yen-Cheng Kung·Duncan K. Maude·Andras Kis·Paulina Plochocka
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Abstract

Monolayer transition metal dichalcogenides (TMDC) grown by chemical vapor deposition (CVD) are plagued by a significantly lower optical quality compared to exfoliated TMDC. In this work we show that the optical quality of CVD-grown MoSe$_2$ is completely recovered if the material is sandwiched in MoS$_2$/MoSe$_2$/MoS$_2$ trilayer van der Waals heterostructures. We show by means of density-functional theory that this remarkable and unexpected result is due to defect healing: S atoms of the more reactive MoS$_2$ layers are donated to heal Se vacancy defects in the middle MoSe$_2$ layer. In addition, the trilayer structure exhibits a considerable charge-transfer mediated valley polarization of MoSe$_2$ without the need for resonant excitation. Our fabrication approach, relying solely on simple flake transfer technique, paves the way for the scalable production of large-area TMDC materials with excellent optical quality.

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Alessandro Surrente, Dumitru Dumcenco, Zhuo Yang, Agnieszka Kuc, Yu Jing, Thomas Heine, Yen-Cheng Kung, Duncan K. Maude, Andras Kis, Paulina Plochocka. 2017-03-02. Defect healing and charge transfer mediated valley polarization in MoS$_2$/MoSe$_2$/MoS$_2$ trilayer van der Waals heterostructures. https://doi.org/10.1021/acs.nanolett.7b00904

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