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Interlayer electron–phonon coupling in WSe2/hBN heterostructures

Nature Physics volume 13, pages 127–131 (2017)Cite this article

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Abstract

Engineering layer–layer interactions provides a powerful way to realize novel and designable quantum phenomena in van der Waals heterostructures1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16. Interlayer electron–electron interactions, for example, have enabled fascinating physics that is difficult to achieve in a single material, such as the Hofstadter’s butterfly in graphene/boron nitride (hBN) heterostructures5,6,7,8,9,10. In addition to electron–electron interactions, interlayer electron–phonon interactions allow for further control of the physical properties of van der Waals heterostructures. Here we report an interlayer electron–phonon interaction in WSe2/hBN heterostructures, where optically silent hBN phonons emerge in Raman spectra with strong intensities through resonant coupling to WSe2 electronic transitions. Excitation spectroscopy reveals the double-resonance nature of such enhancement, and identifies the two resonant states to be the A exciton transition of monolayer WSe2 and a new hybrid state present only in WSe2/hBN heterostructures. The observation of an interlayer electron–phonon interaction could open up new ways to engineer electrons and phonons for device applications.

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Figure 1: WSe2/hBN heterostructures.
Figure 2: Emission spectra of a WSe2/hBN heterostructure at 77 K.
Figure 3: Resonant Raman process in WSe2/hBN heterostructures.
Figure 4: Varying the interlayer electron–phonon coupling with electrostatic doping.

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Acknowledgements

We thank S. Kahn for technical suggestions on heterostructure preparation and J. Yuk for fruitful discussions on sample characterization. This work was primarily supported by the Director, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division of the US Department of Energy under Contract No. DE-AC02-05-CH11231 (van der Waals heterostructures program, KCWF16), and was supported in part by previous breakthroughs obtained through the Laboratory Directed Research and Development Program of Lawrence Berkeley National Laboratory under US Department of Energy Contract No. DE-AC02-05CH11231. F.W. also acknowledges support from a David and Lucile Packard fellowship. S.T. acknowledges support from NSF CAREER award DMR 1552220. Growth of hexagonal boron nitride crystals was supported by the Elemental Strategy Initiative conducted by the MEXT, Japan and a Grant-in-Aid for Scientific Research on Innovative Areas ‘Science of Atomic Layers’ from JSPS.

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Author notes

  1. Chenhao Jin and Jonghwan Kim: These authors contributed equally to this work.

Authors and Affiliations

  1. Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA

    Chenhao Jin, Jonghwan Kim, Zhiwen Shi, Matthew Kam, Alex Zettl & Feng Wang

  2. Department of Materials Science and Engineering, University of California at Berkeley, Berkeley, California 94720, USA

    Joonki Suh & Junqiao Wu

  3. School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, Arizona 85287, USA

    Bin Chen, Xi Fan & Sefaattin Tongay

  4. National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan

    Kenji Watanabe & Takashi Taniguchi

  5. Material Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA

    Alex Zettl, Junqiao Wu & Feng Wang

  6. Kavli Energy NanoSciences Institute at University of California Berkeley and Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA

    Alex Zettl & Feng Wang

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  1. Chenhao Jin
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Contributions

F.W., J.K. and C.J. conceived the research. C.J. and J.K. carried out optical measurements. C.J. and F.W. performed theoretical analysis. J.K., C.J., J.S., Z.S. and M.K. fabricated gate-tunable van der Waals heterostructures. B.C., X.F. and S.T. grew WSe2 crystals. K.W. and T.T. grew hBN crystals. All authors discussed the results and wrote the manuscript.

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Correspondence to Feng Wang.

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The authors declare no competing financial interests.

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Jin, C., Kim, J., Suh, J. et al. Interlayer electron–phonon coupling in WSe2/hBN heterostructures. Nature Phys 13, 127–131 (2017). https://doi.org/10.1038/nphys3928

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