Identifying Raman modes in few-layer WS₂ using Polarized Raman Spectroscopy

The anisotropic properties of low-symmetry 2D materials hold significant promise for next-generation electronics and optoelectronics. 2M-WS₂, as a newly discovered topological superconductor, has attracted substantial interest in recent years. Yet, a comprehensive study of its anisotropic features and the corresponding Raman modes remains to be conducted. In this work, we delve into the Raman modes and their corresponding polarization dependence in 2M-WS₂ thin layers using Raman spectroscopy. Preliminary findings suggest that the intensity of Raman spectra for 2M-WS₂ layers amplifies inversely with sample thickness. Furthermore, a detailed analysis of the polarization-dependent Raman spectra, using two distinct laser excitations, allowed us to identify specific Raman modes, encompassing both A_g and B_g, in few-layer 2M-WS₂. A notable observation is that the different Raman modes demonstrate a clear anisotropic dependence on the laser wavelengths. This study deepens our insight into the anisotropic properties of 2M-WS₂ and highlights the pivotal role of laser wavelength in discerning its crystallographic orientation through Raman spectroscopy.