The effect of BiIn hetero-antisite defects in In1-xPBix alloy

BiIn hetero-antisite defects in InP:Bi alloy is performed by using first-principle calculations. It is found that the hetero-antisite defect BiIn is energetically easier than BiP. This BiIn defect is a deep level donor, and the related defect band is introduced by the sp-hybridization mainly between the 6s state of BiIn and 3p states of the nearest P atoms. The band gap of InP:Bi alloy increases slightly with the increase of Bi compositions, and the relative position of the defect level remains almost unchanged. These results represent that hetero-antisite defect BiIn does not contribute to the reduction of the band gap of InP:Bi alloy. The calculations of optical properties show that hetero-antisite defect BiIn can contribute to the red shift phenomena observed in experiment as the Bi composition increases. In addition, the interaction of two BiIn atoms can result in the split of the impurity band and cause a strong absorption in near-infrared region, indicating it can be a potential candidate for optoelectronics application.