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Strong coupling and pressure engineering in WSe2–MoSe2 heterobilayers

Nature Physics volume 17, pages 92–98 (2021)Cite this article

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Abstract

Two-dimensional materials offer an exciting platform that enables the creation of van der Waals heterostructures with rich functions and intriguing physical properties that stem from different band alignments and diverse interlayer interactions. However, further exploration of two-dimensional van der Waals heterostructures is hindered by the limited coupling strength and lack of efficient methods for tuning the interlayer interactions. Here, by using a two-step chemical vapour deposition method, we realize high-quality 2H-stacked WSe2–MoSe2 heterostructures with strong interlayer coupling, and effective tuning of their interlayer interaction by hydrostatic pressure. We unambiguously establish the strong coupling nature in these WSe2–MoSe2 heterostructures through the existence of exclusive interlayer excitons instead of the typical intralayer excitons. We further demonstrate efficient tuning of the interlayer coupling by using pressure engineering, and observe a clear evolution and transition of interlayer excitons in WSe2–MoSe2 heterostructures with a pressure-induced band changeover, which is further confirmed by first-principles calculations. Our findings provide new opportunities for producing, exploring and tuning van der Waals heterostructures with strong interlayer coupling that can lead towards the realization of future excitonic devices based on tailor-made, atomically thin, two-dimensional stacks.

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Fig. 1: Excitonic and electronic behaviour in 2D heterostuctures.
Fig. 2: CVD-grown 2H WSe2–MoSe2 vdW heterostructures with strong interlayer coupling.
Fig. 3: Pressure engineering of electronic states in strongly coupled WSe2–MoSe2 heterostructures.
Fig. 4: Pressure-induced Raman vibration and band evolution in strongly coupled vdW heterostructures.

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Source data are provided with this paper. All other data that support the plots within this paper and other findings of this study are available from the corresponding authors upon reasonable request.

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Acknowledgements

J.X. and Z.W. acknowledge support from the Ministry of Science and Technology of China (grant no. 2018YFE0115500), the National Natural Science Foundation of China (no. 61774029) and the Science and Technology Department of Sichuan Province in China (nos. 2019JDTD0006 and 2019YFSY0007). J.Y. gratefully acknowledges financial support from the National Natural Science Foundation of China (grant no. 11704185) and the Natural Science Foundation of Jiangsu Province in China (no. BK20171021). Z.S. gratefully acknowledges the Ministry of Education of Singapore for the funding of this research through AcRF Tier 1 grants (nos. RG103/16 and RG195/17) and a Tier 3 grant (no. MOE2016-T3-1-006 (S)). Z.L. acknowledges funding support through a Tier 3 grant (no. MOE2018-T3-1-002), a Tier 2 grant (no. MOE2016-T2-2-153) and the A*STAR Quantum Technologies for Engineering Programme. J.X. and Z.W. thank S. Shi for helpful discussions, and the support from our group members T. Wen, Y. Liang, B. Xu, F. Xiao, J. Zhu, J. Fang, S. Wu, J. Li, Q. Deng, F. Wang and Z. Zhang.

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Authors and Affiliations

  1. Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu, China

    Juan Xia & Zenghui Wang

  2. Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore

    Juan Xia, Jiaxu Yan, Weiqiang Chen, Tze Chien Sum & Zexiang Shen

  3. Key Laboratory of Flexible Electronics (KLOFE) and Institute of Advanced Materials (IAM), Jiangsu National Synergistic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, Nanjing, China

    Jiaxu Yan

  4. School of Materials Science and Engineering, Nanyang Technological University, Singapore, Singapore

    Yongmin He & Zheng Liu

  5. Department of Chemistry and Department of Materials Science and Nanoengineering, Rice University, Houston, TX, USA

    Yongji Gong & Pulickel M. Ajayan

  6. Key Laboratory of Laser Life Science of Ministry of Education and Guangdong Province, College of Biophotonics, South China Normal University, Guangzhou, China

    Weiqiang Chen

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Contributions

J.X., J.Y. and Z.S. conceived the study. J.X. performed the experimental work. J.Y. performed the simulation studies. J.X., Z.W. and J.Y. analysed the data. Y.H. and Z.L. helped to prepare the heterostructure samples. Y.G. and P.M.A. performed the TEM/STEM measurements. W.C. and T.C.S. helped with the ultrafast pump–probe measurements. J.X. and Z.W. wrote and revised the manuscript. All authors discussed the results.

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Correspondence to Juan Xia, Jiaxu Yan, Zenghui Wang or Zexiang Shen.

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Peer review information Nature Physics thanks Fred Withers and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Xia, J., Yan, J., Wang, Z. et al. Strong coupling and pressure engineering in WSe2–MoSe2 heterobilayers. Nat. Phys. 17, 92–98 (2021). https://doi.org/10.1038/s41567-020-1005-7

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