Theoretical Study On Electronic Structure And Optical Properties Of Two-dimensional GaAs

The discovery of two-dimensional material and graphene opens the door with the two-dimensional material world.Because of the graphene special band structure,high strength and high thermal conductivity,it has great potential in the preparation of electronic device radiators and processors.But the structure of zero band gap limits the application of the material in the field of optical devices.III-V group GaAs has been widely studied for its excellent optical and electrical properties,and has been applied to the preparation of opto-electronic and electronic devices.Compared with 2D graphene,3D GaAs has similar structure.Two-dimensional GaAs has little research on photoelectric property and geometry structure.Therefore,it is very important to study two-dimensional GaAs in structure and property.In this paper,the electronic structure and optical properties of ideal and defect two-dimensional GaAs were simulated and calculated by molecular dynamics and first principle method.Another the optical properties of two types are also simulated and calculated under different pressure.The tersoff potential function was used for calculation,and the simulation results were analyzed by visual analysis software.The first principle density functional theory using plane wave pseudopotential quantum mechanics program CASTEP software calculates and analyses of ideal and defeat two-dimensional graphene structure electronic and optical properties GaAs.The analysis of the simulation and calculation of the electronic and optical properties of the ideal two-dimensional graphene-like structure GaAs shows that: two-dimensional GaAs stabilityhas metallic propertybecause the highest two bands are overlapping.This is different from three-dimensional GaAs at the band structures.The lower energy bands of two-dimensional GaAs are composed of Ga d,As s and p,the higher energy bands are composed As s and p states.The results show that the static permittivity of two-dimensional GaAs is 5.36.Two-dimensional GaAs has a strong absorption of ultraviolet light,which show the metallic reflection character in the range of 3.90 ~ 4.71 eV and 5.69 ~ 6.90 eV energy.The electronic structure and optical properties of the two-dimensional defect graphene-like structure GaAs were analyzed.The results show that two-dimensional GaAs with Ga and As vacancy defects exhibits metallic properties.The introduction of B and P atoms makes the system into an indirect band gap semiconductor with a band gap of 0.35 eV and 0.68 eV.The calculation of the density of states shows that the lower-energy band of the system is mainly composed of s states,p states,d states of Ga and s states and p states of As.The higher energy band is mainly composed of s and p states of Ga and As.Compared with the two-dimensional GaAs of vacancy defects,the static dielectric constant of doped B atoms is relatively low.It is easy to absorb ultraviolet light and exhibits metal reflection characteristics in 3.90 ~ 8.63 eV energy range and reflectivity is 52%.The calculated and simulated result of the energy band structure and optical properties of two-dimensional ideal graphene-like GaAs under different pressures show that: with the compression stress increasing,the high-region energy band move to higher energy while the low-region energy band has no change that makes the energy gap widened.The results mean the conductor two-dimensional converts semiconductor.The materials mentalicity is increasing with the tensile stress increasing.Compressing lattice will lead to the blue shift,increasing the absorption index and reflection index of Ultraviolet light,while stretching force result in the red shift,decreasing the absorption index and reflection index of Ultraviolet light.The stress increases the reflectivity of the material reflecting the metal reflectivity in a specific energy range.In addition,the pressures increases the absorption range of the material to the light.The analysis of the band structure and optical properties of two dimensional graphene GaAs with point defects under different pressure shows that the band structure of two-dimensional with Ga vacancy and As vacancy defect does not change with the isotropic stress,continuing to show the metal properties.The band gap of B doped and P doped two-dimensional GaAs is dependent on the band gap.As the pressure increases,it tends to wide band gap semiconductors.With the increase of the tension,the band gap vanishes.The materal is transformed from semiconductor to conductor,and the metal properties are graduall-y enhanced.The absorptivity of B doped and P doped GaAs increases with the increase of pressure,the absorption intensity increases,and the absorption peak moves towards the high energy range,and the blue shift occurs.As the tension increases,the absorption intensity decreases,and the absorption peak moves towards the lower energy range,and the red shift occurs.