title: Characterization of Few-Layer 1T' MoTe2by Polarization-Resolved Second Harmonic Generation and Raman Scattering.
abstract: We study the crystal symmetry of few-layer 1T' MoTe2using the polarization dependence of the second harmonic generation (SHG) and Raman scattering. Bulk 1T' MoTe2is 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' MoTe2and 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.
authors.affiliation: Material Measurement Laboratory, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States.
authors.forename: Ryan
authors.initials: R
authors.lastname: Beams
authors.affiliation: Departamento de Física, Universidade Federal de Minas Gerais , Belo Horizonte, Minas Gerais 30123-970, Brazil.
authors.forename: Luiz Gustavo
authors.initials: LG
authors.lastname: Cançado
authors.affiliation: Material Measurement Laboratory, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States.|Theiss Research , La Jolla, California 92037, United States.
authors.forename: Sergiy
authors.initials: S
authors.lastname: Krylyuk
authors.affiliation: Material Measurement Laboratory, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States.
authors.forename: Irina
authors.initials: I
authors.lastname: Kalish
authors.affiliation: Material Measurement Laboratory, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States.
authors.forename: Berç
authors.initials: B
authors.lastname: Kalanyan
authors.affiliation: Material Measurement Laboratory, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States.
authors.forename: Arunima K
authors.initials: AK
authors.lastname: Singh
authors.affiliation: Material Measurement Laboratory, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States.
authors.forename: Kamal
authors.initials: K
authors.lastname: Choudhary
authors.affiliation: Material Measurement Laboratory, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States.
authors.forename: Alina
authors.initials: A
authors.lastname: Bruma
authors.affiliation: Department of Physics and Astronomy, George Mason University , Fairfax, Virginia 22030, United States.
authors.forename: Patrick M
authors.initials: PM
authors.lastname: Vora
authors.affiliation: Material Measurement Laboratory, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States.
authors.forename: Francesca
authors.initials: F
authors.lastname: Tavazza
authors.affiliation: Material Measurement Laboratory, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States.
authors.forename: Albert V
authors.initials: AV
authors.lastname: Davydov
authors.affiliation: Material Measurement Laboratory, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States.
authors.forename: Stephan J
authors.initials: SJ
authors.lastname: Stranick
keywords: Raman scattering; crystal symmetry; optical spectroscopy; second harmonic generation; two-dimensional material