First Principles Study On Electronic Structure And Optical Properties Of Transition Metal Disulfide VdW Heterostructure

In the field of modern materials science,low-dimensional materials are widely used in optoelectronic devices and integrated optical circuits.In recent years,two-dimensional（2D）materials and devices,such as graphene and transition metal disulfides（TMDs）have shown very excellent performance and attracted wide application interests.Therefore,2D materials have rapidly become a hot research field.However,there are still some problems,from the design of device structure,to the fabrication process of materials.Further design of TMDs devices with high quantum efficiency is also one of the important points for academic research and industrial applications.When designing TMDs devices,accurate electronic optical parameters are essential.The optical parameters of typical 2D materials are not isotropic,but normally anisotropic.After different 2D materials are stacked vertically to form a heterostructure,the two materials will no longer retain their original characteristics,such as electronic structure and optical properties,leading to the change of corresponding properties.In this paper,first principle calculation based on the density functional theory（DFT）is used.On the one hand,several vertical（van der Waals,vd W）heterostructures with adjustable multifunctionals were designed,on the other hand,corresponding research and analysis on the conventional regulation and control methods（such as strain,external electric field or intercalation）in the heterostructures were conducted.The specific research contents and results of this article are as follows:（1）DFT was used to simulate the multilayered HfS₂/Mo Te₂ vd W heterostructure.Under uniaxial strain perpendicular to the 2D plane,the heterostructure exhibits a transition from semiconductor to metal.The effective mass of the carrier and optical properties of the heterostructure are found to be modulated under external strain,indicating that the heterostructure has a good piezoelectric effect.（2）Based on DFT calculations,the properties of vd W heterostructures based on TMDs-Re X₂（X=S,Se）were studied.In the process of changing the applied electric field,the band gap of the heterostructure shows tenability.In addition,the ReS₂/ReSe₂ heterostructure shows good light absorption characteristics in the visible region,indicating an effective method for the design of new vd W heterostructures based on TMDs,which can be used in optical devices.（3）Using first-principles calculations,we studied the electrical and optical properties of the vd W trilayer heterostructure.By inserting a 2D monolayer material（ML=graphene and boron nitride BN）between WSe₂/SnS₂ bilayer,WSe₂/ML/SnS₂ sandwich structures are formed.For different WSe₂/ML/SnS₂ sandwich structures,they have different band gaps and properties.The sandwich structure has a higher optical absorption rate than the bilayer structure,and is suitable for efficiently absorbing ultraviolet light and near-visible light.The research work of this paper might not only have certain guiding significance for the design of new 2D materials and heterostructures,but also have valuable theoretical reference for the design of photodetectors and integrated optical devices.