X-ray absorption study of the atomic environment in Sb+ and Sb+/B+ implanted silicon

The electrical deactivation of Sb atoms highly implanted (2 and 5×1016 ions/cm2) in crystalline silicon is studied by the extended x-ray absorption fine structure (EXAFS) method. By following the evolution of the local atomic environment around the Sb atoms it is shown that the description of the deactivation process must take into account the existence of vacancy complexes, SbV2, in addition to the usual antimony rhombohedric precipitates. These vacancy complexes are already present after laser annealing in the 5×1016 ions/cm2 case. Co-implantation with boron delays the precipitation of Sb particles, by forming new complexes, SbBV or SbB2, with a Sb atom surrounded by two sites (B and/or vacancy).