First Principle Study The Influence Of Strain And Doping On The Photoelectric Properties Of InN And GaN

Gallium nitride and Indium nitride,the third generation of semiconductor materials,shows a high electron saturation rates,high electron mobility,less effective electron mass,good thermal conductivity and stable physical and chemical properties.Thus,Group III nitrides(GaN,InN)in production of high-power short-wave electronic components shows a huge application prospects,which is considered to be the most promising short-wave optoelectronic device materials.The electrical structure of GaN and InN can be changed by strain and doping,thereby changing their electrical and optical properties.Although good results on the effects of strained and Be,Mg co-doped GaN and the influence of strain on the In N photoelectric properties have been theoretically and experimentally achieved,there are still some deficiencies need to further study.In this paper,the influence of Be and Mg doping on the electronic structure and absorption spectra of Ga N were studied by the generalized gradient approximation(GGA)method under the density functional theory(DFT).The calculated results show that with the increase of Be and Mg doping concentration in the range of 0.02083-0.0625,the lattice constant,volume,total energy and the formation energy of the doped systems increases,the stability of the doped systems decreases,and the doping becomes more difficult.With the increase of the doping concentration,the bandgap are widened and the absorption spectra show a blue-shift.With the increase of the doping concentration in the doping concentration range,the hole effective mass decreases first and then increases,the mobility increases,and the conductivity increases first and then decreases.The effects of strain on the electronic structure and optical properties of wurtzite GaN are studied by using the generalized gradient approximation(GGA + U)under the first-principles density functional theory(DFT)framework.The results show that the lattice constant of GaN decreases first and then increases with the increase of tensile strain,and decreases with the increase of compressive strain.The bandgap increases first and then decreases with the increase of tensile strain,and increase with the increase of compressive strain.The changing trend of absorption spectrum is consistent with the bandgap,blue shift is observed when the 1% tensile strain is applied,and then the red shift is continued.Furthermore,the absorption spectrum red-shifts at compressive strain.The electronic structure and optical properties of InN with strain are calculated by using the generalized gradient approximation(GGA).The results show that the bandgap is narrowed as the strain increase,and the change of bandgap is linear with the strain.The static permittivity,refractive index,energy loss function under the biaxial compressive strain are no significant change and increases at tensile strain,and it is more obvious at uniaxial tension strain than that under biaxial tension strain.The imaginary part of the dielectric function has the same number of peaks in the uniaxial and biaxial compressive strain.The absorption spectra are red shifted at uniaxial compressive,tensile strain and biaxial compressive strain,bur blue shifted at biaxial tensile strain.Other optical properties also vary significantly change with strain.