Raman scattering investigation of twisted WS2/MoS2 heterostructures: interlayer mechanical coupling versus charge transfer

Lishu Wu, Chunxiao Cong*, Jingzhi Shang*, Weihuang Yang, Yu Chen, Jiadong Zhou, Wei Ai, Yanlong Wang, Shun Feng, Hongbo Zhang, Zheng Liu, Ting Yu*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

40 Citations (Scopus)

Abstract

Twisted van der Waals homo- and hetero-structures have aroused great attentions due to their unique physical properties, providing a new platform to explore the novel two-dimensional (2D) condensed matter physics. The robust dependence of phonon vibrations and electronic band structures on the twist angle has been intensively observed in transition metal dichalcogenide (TMD) homo-structures. However, the effects of twist angle on the lattice vibrational properties in the TMD heterostructures have not caused enough attention. Here, we report the distinct evolutions of Raman scattering and the underlying interlayer interactions in the twisted WS2/MoS2 heterostructures. The shifts and linewidths of E2g(Γ) and A1g(Γ) phonon modes are found to be twist angle dependent. In particular, analogous to that of the twisted TMD homostructures, the frequency separations between E2g(Γ) and A1g(Γ) modes of MoS2 and WS2 in the twisted heterostructures varying with twist angle correlate with the interlayer mechanical coupling, essentially originating from the spacing-related repulsion between sulfur atoms. Moreover, the opposite shift behaviors and broadening of A1g(Γ) modes caused by charge transfer are also observed in the twisted heterostructures. The calculated interlayer distances and band alignment of twisted WS2/MoS2 through density functional theory further evidence our interpretations on the roles of the interlayer mechanical coupling and charge transfer in variations of Raman features. Such understanding and controlling of interlayer interaction through the stacking orientation are significant for future optoelectronic device design based on the newly emerged 2D heterostructures. [Figure not available: see fulltext.]

Original languageEnglish
Pages (from-to)2215-2223
Number of pages9
JournalNano Research
Volume14
Issue number7
DOIs
Publication statusPublished - Jul 2021
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2021, Tsinghua University Press and Springer-Verlag GmbH Germany, part of Springer Nature.

ASJC Scopus Subject Areas

  • Atomic and Molecular Physics, and Optics
  • General Materials Science
  • Condensed Matter Physics
  • Electrical and Electronic Engineering

Keywords

  • charge transfer
  • interlayer coupling
  • Raman scattering
  • twist angle
  • van der Waals heterostructures

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