First-principles Study Of Two-dimensional Semiconductor Material InSe Based Van Der Waals Heterostructure

The successful preparation of graphene has sparked research interest in two-dimensional materials.Due to its unique structure and excellent performance,two-dimensional materials are widely considered to have infinite application potential in the future of electronics and optoelectronics.However,a single two-dimensional material has more or less certain performance defects.With the continuous research of researchers in various countries,it has been found that stacking two kinds of two-dimensional materials to form a van der Waals heterojunction can avoid the defects of a single material and exhibit some novel performance.Therefore,the research on two-dimensional van der Waals heterojunction has been one of the hotspots of current research.In this paper,we use the material simulation software Materials Studio to establish the models,and use the first-principles method based on density functional theory to study the structure and photoelectric properties of InSe/arsenene heterojunction and InSe/h-BN heterojunction.The research results are as follows:(1)Firstly,the first-principles method based on density functional theory was used to study the electronic properties of single-layer two-dimensional semiconductor materials InSe and arsenene,and InSe/arsenene heterojunctions.The calculation results of the band structure show that the InSe/arsenene heterojunction band gap is 0.876 eV,which is smaller than the band gap of the single layer InSe and arsenene.The heterojunction band gap type is a direct band gap,which can effectively improve the photoluminescence efficiency.It can be seen from the band diagram that the InSe/arsenene bilayer structure forms a type-II van der Waals heterojunction,which is beneficial to the separation of photogenerated electron-hole pairs.Optical properties studies have shown that the InSe/arsenene heterojunction exhibits stronger absorption of ultraviolet light and absorption of some visible light,and has a higher optical absorption intensity.These results indicate that the InSe/arsenene heterojunction has certain application value in the field of micro-optoelectronic devices in the future.(2)Secondly,considering that the heterojunction is always regulated by external conditions in practical applications,we studied the effects of applied electric field and uniaxial strain on the properties of InSe/arsenene heterojunction.The calculation results show that the external electric field and uniaxial strain can effectively adjust the InSe/arsenene heterojunction properties.When an external electric field is applied,the heterostructure experiences a transition from a semiconductor to metal.In addition,due to the presence of a built-in electric field,the positive and negative electric fields have different effects on the electronic properties of the heterostructure.When uniaxial strain is applied,the heterostructure can withstand larger tensile strain than compression strain without damaging the structure and the band gap is more easily decreased by X-direction strain.In addition,the heterostructure undergoes a directindirect bandgap transition under strain.When compressive strain is applied in the Y direction,especially ?<-2%,the heterostructure possesses higher carrier mobility while maintaining direct bandgap characteristics.Under the control of the external electric field and strain,InSe/arsenene heterojunction can exhibit excellent performance,which further proves its application potential.(3)Finally,we calculated and analyzed the structural and electronic properties of the three InSe/h-BN heterojunctions.We find that the InSe /h-BN heterostructures show indirect bandgap features with both of CBM and VBM localized on the monolayer InSe.Difference charge density indicates that there is no obvious charge exchange between layers.By calculating the energy band structure of the system,we find that the h-BN layer has a significant regulatory effect on the monolayer InSe.Comparing the energy band structure of monolayer InSe under pure strain control,it is found that the regulation effect of h-BN on InSe band structure is caused by the lattice strain induced by the interaction between InSe and h-BN.Our results show that a monolayer of InSe can be deposited or grown on different h-BN sheets to obtain different lattice strains,which can effectively control the single-layer InSe energy band.This finding provides some theoretical guidance for achieving a change in the atomic precision orientation of the band gap of InSe.