Ab initio studies of CiCs and CiOi defects in Si1-xGex alloys
Si1-xGex合金半导体中CiCs和CiOi缺陷随Ge含量的变化

Ab inltio total-energy calculations were used to investigate the behaviors of CiCs and CiOi defects in Si and Si1-x Gex alloys. It was found that in Si1-x Gex alloys with different Ge contents, both CiCs and CiOi defects have good stability, and direct Ge-C or Ge-O bonds are unlikely to be formed. The A and B type structures of CiCs defects have similar characters in the alloys. The formation energy of A type configuration decreases with increasing Ge content. But the formation energy of B type decreases at first and then increases with the Ge content. The energy differences of A and B type configuration defects are between 0. 235 and 0. 220 eV with lower Ge contents, and decrease sharply to around 0.1 eV for higher Ge contents. The formation energy of CiOi pair displays a complex feature. Under isothermal annealing at 1000 K and above, the structure of A type Ci Cs defect in pure Si was destroyed and transformed to B type defect. During annealing, the behavior of A type CiCs defect in Si1-x Gex alloys depended on the annealing temperature, Ge content in the alloy, and the sites of Ge atoms.