Lattice Vibration And Raman Spectrum Of Monolayer And Bilayer Indium Selenide

Raman spectroscopy plays an important role in studying the structure of lattice because of its high sensitivity,rapidity and rich information.However,there are still some difficulties in relevant experimental studies,such as overlapping band of different components in a mixture,nonlinear mixture effects of spectra and so on.We use the first principle to calculate the Raman vibration characteristic of 2D material,which provides theoretical basis for the experimental design and related research.In the paper,we optimize the structure and calculate the phonon dispersion of monolayer and bilayer InSe.Based on this results,we obtain their Raman spectrum,and study the characteristics of crystal structure,lattice vibration,and structure symmetry.We also calculate the depolarization ratio of monolayer InSe.Finally,we study the variation of the Raman scattering intensity of monolayer In Se with incident light,and discuss four situations in which the polarization of incident light and scattered light are parallel/perpendicular and in the xy/xz plane.Our results indicate that the monolayer InSe has stable structure.There are four peaks in the Raman spectrum of monolayer InSe,and an dominant peak corresponding to mode A'.We investigate that several peaks in the Raman spectrum.And A₁ modes can simulate obvious Raman scattering phenomenon;we also obtain the depolarization of mode A' with two peaks are highly polarized bands according to the depolarization ratio.For monolayer In Se,the Raman tensor A' and E'corresponding Raman scattering do not change with the angle of incident light,when the polarization of incident light is parallel to the scattered light,and is in the xy plane.When the polarization of incident light is perpendicular to the scattered light,and is in the xy plane,the Raman tensor A' dose not cause the Raman scattering phenomenon.This indicates that the angel between incident light and scattered light also affects Raman scattering intensity.When the polarization of incident light is parallel to the scattered light,and is in the xz plane,Raman tensor A' corresponding to the Raman scattering intensity is not only related to the angle of incident light,but also the ratio of b to a of the Raman tensor matrix.When the polarization of incident light is perpendicular to the scattered light,and is in the xz plane,the ratio of elements b and a of Raman tensor needs to have a smaller value.In this case,Raman tensor A' can cause obvious Raman scattering phenomenon.