First Principle Study On Two-dimensional Semiconductor ReSe₂-based Van Der Waals Heterostructures

Two-dimensional transition metal dichalcogenides(TMDs)materials have been a hot research topic in recent years,both in experiments and theories.However,single two-dimensional(2D)materials have some shortcomings more or less.Therefore,the heterostructure constructed by two or more two-dimensional layered materials is expected to obtain some novel properties.In addition,the improvement of computer performance and density functional theory made software calculation based on the first principle of density functional theory as an important research method in the field of condensed matter physics.In this paper,the construction of the model is completed with the help of the software Materials Studio,and the geometric configuration,electronic structure,and optical properties of the monolayer ReSe₂ and monolayer Mo Se₂ and the corresponding heterostructures are systematically studied by the VASP application software package.And put forward the best construction type of ReSe₂/Mo Se₂.The research results have a certain reference value and guiding significance for the preparation of UV detectors and other optoelectronic devices.The main results are as follows:(1)Studied the structure,electronic,and optical properties of the van der Waals(vd W)heterostructure systematically for the first time,which is the construction by the ReSe₂ monolayer and Mo Se₂ monolayer.Ten different configurations of the above heterostructures were studied,and the structure optimization and the calculation of the band structure of them are carried out respectively.It is found that the properties of the heterostructure are related to the stacking order for the ReSe₂ and Mo Se₂ layers,which are mainly affected by their symmetry.Only the optical properties and band alignment of configuration VI were calculated.It reveals that the band alignment belongs to type-II,and had a certain band order,which was beneficial to the separation of photogenerated electrons and holes effectively.In addition,the ReSe₂ and Mo Se₂ layers of configuration VI still maintain similar electronic characteristics with monolayer,only the band gap values were slightly reduced.The absorption performance of the heterostructure is greatly improved than that of the individual component materials,and the absorption coefficient in the visible and UV light region is up to the order of 10~5 cm^-1.(2)Research on the two-dimensional ReSe₂/Mo Se₂ vd W heterostructure based on configuration VI.The regulation effects of vertical strain and horizontal biaxial strain on the ReSe₂/Mo Se₂ vd W heterostructure were further considered.According to the research,the effects of the vertical strain on the structure of the ReSe₂/Mo Se₂ vd W heterostructure are slight.Compared with tensile strain,the compressive strain has a greater effect on the bandgap,but neither changes the type of band alignment with the ReSe₂/Mo Se₂ vd W heterostructure.The light absorption coefficient increases significantly with an increase in vertical compressive strain and decreases slightly with an increase in vertical tensile strain.The horizontal biaxial strain has a significant influence on the structure of ReSe₂/Mo Se₂ vd W heterostructure,which will cause the formation and breakage of interatomic bonds,and change the conductive properties of the heterojunction.In other words,a transition between semiconductors and metal occurs.Nevertheless,it still showed relatively strong light absorption efficiency in the visible and UV regions.The above results indicate that the ReSe₂/Mo Se₂ vd W heterojunction is a promising candidate material for optoelectronic applications.