| Low dimensional semiconductor materials with special structure and excellent properties are expected to produce new devices with multiple functions and applications.Realizing multi-function,intelligence,miniaturization and flexible wearable as well as green environmental protection,to meet the new demand of science and technology development,so it is favored by researchers,GaAs material has attracted much attention due to its excellent photoelectric properties.By doping GaAs material modification,and GaAs material and other materials transverse or longitudinal combination as heterojunction,researchers get heterogeneous junction devices with various uses and functions.Based on density functional theory(DFT),this paper adopts first-principles calculation method and combines the materials science of low-dimensional system.The photoelectric properties of two-dimensional GaAs intrinsic and doped materials and two-dimensional GaAs/InAs heterostructure materials are calculated and analyzed,and the following results are obtained:(1)The crystal direction of sphalerite GaAs[110],[110]and[101]was selected as the section to construct a two-dimensional GaAs structure model,calculate and analyze the photoelectric characteristics of the material,and compare it with the three-dimensional sphalerite GaAs material.The results showed that the photoelectric properties of the three two-dimensional structural materials were not significantly different.The gap width was 1.41 eV,which was not significantly different from that of the three GaAs materials,but the band gap type changed into indirect band gap.Compared with 3D materials,the peak values of real and imaginary parts of the dielectric constant decrease.The absorption coefficient increases,the absorption of light is enhanced,the peak value of the reflection spectrum decreases,and the redshift occurs at the same time.The minimum transmittance is 81%,which indicates that the three kinds of two-dimensional gallium arsenide materials have good light transmittance.(2)The crystal direction of sphalerite structure GaAs[110]was selected as the section,and the In doping group was divided into(x=3.13%,6.25%,9.375%and 12.5%)to construct a two-dimensional Ga1-xInxAs as material structure model.The photoelectric characteristics of the material were calculated and analyzed,and compared with the two-dimensional intrinsic gallium arsenide material.The results showed that the bandgap widths were 1.39 eV,1.37 eV,1.34 eV and 1.30 eV respectively,which decreased with the increase of doping ratio and was also smaller than the band gap of 2D intrinsic GaAs.With the increase of In doping ratio,the peak values of the real part,the imaginary part,the absorption coefficient and the reflection coefficient all gradually decrease,and the energy region of the absorption peak and the reflection peak becomes wider,and the transmittance gradually increases.(3)The crystal direction of sphalerite structure GaAs[110]was selected as the section,and the Cu doped group was divided into 3.13%two-dimensional Ga1-xCuxAs as material structure model,and the photoelectric characteristics of the material were calculated and analyzed.The results show that the band gap type is also an indirect band gap,with a gap width of 1.48 eV and impurity level,which is mainly caused by a small amount of As-4p,Ga-4p and Cu-3d formed in the energy region of 0.09 eV～0.33 eV near the Fermi level.Compared with the 2D intrinsic GaAs material,the peak values of the real and imaginary parts of the dielectric constant of Cu doping system increased,the absorption coefficient and reflection coefficient increased,and the transmittance decreased.The results show that Cu doping increases the electromagnetic wave absorption and reflection ability and decreases the transmittance of GaAs.(4)Select sphalerite structure GaAs[110]and crystal orientation of InAs[110]as sections to construct two-dimensional GaAs,InAs and GaAs/InAs heterostructure models to calculate and analyze the electronic structure of materials.The results show that the bandgap widths of two-dimensional GaAs and InAs are 1.41 eV and 1.28 eV respectively,which belong to indirect band gap.The gap width of two-dimensional GaAs/InAs heterostructure is 0.81 eV,and the band gap is the direct band gap.It belongs to the first class heterojunction and can be applied to LED and laser devices. |
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