1. Characterization of Few-Layer 1T′ MoTe2 by Polarization-Resolved Second Harmonic Generation and Raman Scattering
- Author
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Patrick M. Vora, Stephan J. Stranick, Albert V. Davydov, Berc Kalanyan, Alina Bruma, Francesca Tavazza, Sergiy Krylyuk, Kamal Choudhary, Luiz Gustavo Cançado, Irina Kalish, Ryan Beams, and Arunima K. Singh
- Subjects
business.industry ,Chemistry ,General Engineering ,Second-harmonic imaging microscopy ,Physics::Optics ,General Physics and Astronomy ,Second-harmonic generation ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Polarization (waves) ,01 natural sciences ,Molecular physics ,0104 chemical sciences ,symbols.namesake ,X-ray Raman scattering ,Optics ,symbols ,General Materials Science ,Coherent anti-Stokes Raman spectroscopy ,0210 nano-technology ,Raman spectroscopy ,Anisotropy ,business ,Raman scattering - 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.
- Published
- 2016
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