Characterization of few-layer 1T′ MoTe2 by polarization-resolved second harmonic generation and Raman scattering

Ryan Beams, Luiz Gustavo Cançado, Sergiy Krylyuk, Irina Kalish, Berç Kalanyan, Arunima K. Singh, Kamal Choudhary, Alina Bruma, Patrick M. Vora, Francesca Tavazza, Albert V. Davydov, Stephan J. Stranick

Research output: Contribution to journalArticle

59 Scopus citations

Abstract

We study the crystal symmetry of few-layer 1T′ MoTe2 using the polarization dependence of the second harmonic generation (SHG) and Raman scattering. Bulk 1T′ MoTe2 is known to be inversion symmetric; however, we find that the inversion symmetry is broken for finite crystals with even numbers of layers, resulting in strong SHG comparable to other transition-metal dichalcogenides. Group theory analysis of the polarization dependence of the Raman signals allows for the definitive assignment of all the Raman modes in 1T′ MoTe2 and clears up a discrepancy in the literature. The Raman results were also compared with density functional theory simulations and are in excellent agreement with the layer-dependent variations of the Raman modes. The experimental measurements also determine the relationship between the crystal axes and the polarization dependence of the SHG and Raman scattering, which now allows the anisotropy of polarized SHG or Raman signal to independently determine the crystal orientation.

Original languageEnglish (US)
Pages (from-to)9626-9636
Number of pages11
JournalACS nano
Volume10
Issue number10
DOIs
StatePublished - Oct 25 2016

Keywords

  • Raman scattering
  • crystal symmetry
  • optical spectroscopy
  • second harmonic generation
  • two-dimensional material

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

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    Beams, R., Cançado, L. G., Krylyuk, S., Kalish, I., Kalanyan, B., Singh, A. K., Choudhary, K., Bruma, A., Vora, P. M., Tavazza, F., Davydov, A. V., & Stranick, S. J. (2016). Characterization of few-layer 1T′ MoTe2 by polarization-resolved second harmonic generation and Raman scattering. ACS nano, 10(10), 9626-9636. https://doi.org/10.1021/acsnano.6b05127