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Electrical tuning of optically active interlayer excitons in bilayer MoS2

Nature Nanotechnology volume 16, pages 888–893 (2021)Cite this article

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Abstract

Interlayer (IL) excitons, comprising electrons and holes residing in different layers of van der Waals bonded two-dimensional semiconductors, have opened new opportunities for room-temperature excitonic devices. So far, two-dimensional IL excitons have been realized in heterobilayers with type-II band alignment. However, the small oscillator strength of the resulting IL excitons and difficulties with producing heterostructures with definite crystal orientation over large areas have challenged the practical applicability of this design. Here, following the theoretical prediction and recent experimental confirmation of the existence of IL excitons in bilayer MoS2, we demonstrate the electrical control of such excitons up to room temperature. We find that the IL excitonic states preserve their large oscillator strength as their energies are manipulated by the electric field. We attribute this effect to the mixing of the pure IL excitons with intralayer excitons localized in a single layer. By applying an electric field perpendicular to the bilayer MoS2 crystal plane, excitons with IL character split into two peaks with an X-shaped field dependence as a clear fingerprint of the shift of the monolayer bands with respect to each other. Finally, we demonstrate the full control of the energies of IL excitons distributed homogeneously over a large area of our device.

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Fig. 1: Gated van der Waals heterostructure device and room-temperature IL exciton (device A).
Fig. 2: Electrical control of IL excitons at T = 4 K.
Fig. 3: Calculated evolution of the absorption spectrum of bilayer MoS2 in a perpendicular electric field Fz.
Fig. 4: Electrical switching of large-area IL excitons.

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Data availability

The authors declare that the main data supporting the findings of this study are available within the Article and its Supplementary Information. Extra data are available from the corresponding author upon reasonable request.

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Acknowledgements

T.D. acknowledges financial support from the German Research Foundation (DFG Projects No. DE 2749/2-1) and computing time granted by the John von Neumann Institute for Computing (NIC) and provided on the super-computer JUWELS at the Jülich Supercomputing Centre (JSC). The Center for Nanostructured Graphene (CNG) is sponsored by the Danish National Research Foundation, Project DNRF103. This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program grant agreement No. 773122 (LIMA). S.R. acknowledges financial support from The Leverhulme Trust (Research Grant “Quantum revolution”) and EPSRC (EP/V048163/1 and EP/K010050/1). M.F.C. acknowledges financial support from the EPSRC (EP/V052306/1, EP/M002438/1 and EP/M001024/1).

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Authors and Affiliations

  1. Centre for Graphene Science, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, UK

    Namphung Peimyoo, Freddie Withers, Janire Escolar, Darren Nutting, Monica Felicia Craciun & Saverio Russo

  2. Institut für Festkörpertheorie, Westfälische Wilhelms-Universität Münster, Münster, Germany

    Thorsten Deilmann

  3. International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan

    Takashi Taniguchi & Kenji Watanabe

  4. Department of Materials and Production, Aalborg University, Aalborg, Denmark

    Alireza Taghizadeh

  5. CAMD, Department of Physics, Technical University of Denmark, Kongens Lyngby, Denmark

    Alireza Taghizadeh & Kristian Sommer Thygesen

  6. Center for Nanostructured Graphene (CNG), Department of Physics, Technical University of Denmark, Kongens Lyngby, Denmark

    Alireza Taghizadeh & Kristian Sommer Thygesen

Authors
  1. Namphung Peimyoo
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  11. Saverio Russo
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Contributions

N.P. conceived the idea, fabricated the devices, performed room-temperature measurements and analysed data. T.D. and K.S.T performed the ab initio calculations. F.W. performed low-temperature measurements and corresponding analysis. J.E. contributed to device fabrication. D.N. conducted AFM measurements. K.W. and T.T. produced the bulk hBN crystals. A.T. performed the transfer matrix method calculation. M.F.C. and S.R. supervised the project and suggested the analysis of differential optical spectra. N.P., T.D., M.F.C., K.S.T and S.R. co-wrote the manuscript.

Corresponding author

Correspondence to Saverio Russo.

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The authors declare no competing interests.

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Peer review information Nature Nanotechnology thanks Yuya Shimazaki and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary Information

Supplementary text and Figs. 1–6.

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Peimyoo, N., Deilmann, T., Withers, F. et al. Electrical tuning of optically active interlayer excitons in bilayer MoS2. Nat. Nanotechnol. 16, 888–893 (2021). https://doi.org/10.1038/s41565-021-00916-1

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