First Principles Study Of Point Defects And Co And Ni Doped In

InP is a very important Ⅲ-Ⅴ compound semiconductor material,in which doping magnetic ions such as transition metal or rare earth elements can turn it into diluted magnetic semiconductor,and InP material is widely used in optoelectronics,spintronics,solar cells and other fields.The photoelectric and magnetic properties of InP materials can be effectively improved by adjusting point defects and transition metal doping.Based on the Density Functional Theory(DFT),a systematic study of point defects,Co,Ni doping and Co,Ni doping together with point defects in InP is carried out in this paper using the first principle approach.(1)InP models with point defects are calculated and analyzed.The lattices of vacancy and P-antisite defect models shrink,while the lattices of interstitial and In-antisite defect models expand.The defect energy levels introduced by point defects shift the conduction band down or valence band up,thus the forbidden band becomes narrower and the conductivity is enhanced.The total density of states of the point defect models all shift to the low-energy region.The formation energies of In vacancy,P interstitial and P antisite defect models are relatively small,indicating these are relatively easy to form.The average reflectances of InP models with point defects decrease,the absorption coefficient increases in the near-infrared region,and the light absorption performance is enhanced.The energy loss peak intensity of In vacancy defect remains unchanged,while the energy loss peak intensity of other point defect models decreases.(2)Co and Ni doped InP models are calculated and studied.Co and Ni doping both cause lattice shrinkage.When Co and Ni doping concentration is 3.125%,Co doping introduces impurity level in the forbidden band and the width of forbidden band becomes smaller.And the net magnetic moment is formed near the Fermi level,which exhibits semi-metallic property.After doping Co,Ni,the static dielectric constants of models increase,the absorption edges move to the low-energy region,the positions of energy loss peaks move to the high-energy region,and the intensities of the energy loss peak are reduced.When Co and Ni doping concentration is 6.25%,Co doping still produces a net magnetic moment near the Fermi level,while the net magnetic moment produced by Ni doping is almost 0 at the Fermi energy level.After doping Co and Ni,the static dielectric constant increases,the absorption edges and peak positions of the absorption coefficients all move to the low-energy region,the values of energy loss peak decrease,and the positions of energy loss peak move to the high-energy region.(3)Co and Ni doped InP models with point defects are calculated and studied.P interstitial defect and Co/Ni doping cause the lattice expansion,while In vacancy and P-antisite defects and Co/Ni doping cause the lattice shrinkage.The formation energy of Co/Ni doped InP with P interstitial is the smallest among these,and it is a stable structure easiest to form.The band gaps of Co/Ni doped InP models with point defects become narrower and the densities of states at the Fermi level become larger.Co doped InP model with P interstitial generates net magnetic moment,but the magnetic moments of rest of the models are close to 0.Compared with Co doped InP model,the static dielectric constant of Co doped InP models with In vacancy and P antisite defects increases,while the static dielectric constant of Co doped InP model with P interstitial remains unchanged.The reflectivity and absorption coefficient of Co doped InP models with point defects increase.Compared with Ni doped InP,the static dielectric constant and reflectivity of Ni doped InP models with point defects all decrease,and the absorption edges all move to the high-energy region.