Sensitive Phonon-Based Probe for Structure Identification of 1T′ MoTe₂

In this work, by combining transmission electron microscopy and polarized Raman spectroscopy for the 1T′ MoTe₂ flakes with different thicknesses, we found that the polarization dependence of Raman intensity is given as a function of excitation laser wavelength, phonon symmetry, and phonon frequency, but has weak dependence on the flake thickness from few-layer to multilayer. In addition, the frequency of Raman peaks and the relative Raman intensity are sensitive to flake thickness, which manifests Raman spectroscopy as an effective probe for thickness of 1T′ MoTe₂. Our work demonstrates that polarized Raman spectroscopy is a powerful and nondestructive method to quickly identify the crystal structure and thickness of 1T′ MoTe₂ simultaneously, which opens up opportunities for the in situ probe of anisotropic properties and broad applications of this novel material.