Identification of boron clusters and boron-interstitial clusters in silicon

The identity of boron clusters and boron interstitial clusters in Si, produced by radiation or implantation, has been studied theoretically. Local vibration modes of the single-boron interstitial and the diboron split interstitial (B₂I) and its metastable isomer as well as substitutional dimers are found to be in good agreement with observations. The modes of a diboron defect that has trapped three interstitials B₂I₃ are close to those observed for the boron-related I2 luminescent center. The annealing of these centers around 400°C coincides with the main recovery of the electrical activity of boron, but the formation of defects which are metastable casts doubt on previous modeling strategies.