Thermally activated reorientation of di-interstitial defects in silicon

We propose a di-interstitial model for the P6 center commonly observed in ion-implanted silicon. The di-interstitial structure and transition paths between different defect orientations can explain the thermally activated transition of the P6 center from low-temperature C-1h to room-temperature D-2d symmetry. The activation energy for the defect reorientation determined by ab initio calculations is 0.5 eV, in agreement with the experiment. Our di-interstitial model establishes a link between point defects and {311} defects, supporting the growth model by interstitial nucleations.