Vacancy-Fluorine Clusters in Silicon

Fluorine (F) doping and the formation of F-vacancy $(F_{n}V_{m})$ clusters have been extensively studied in silicon (Si) as they can suppress the transient self-interstitial mediated diffusion of boron (B). Recent experimental studies by Bernardi et al. revealed that there is no significant concentration of $F_{n}V_{m}$ clusters (for n ≥ 4, m ≥ 1) in disagreement with a number of density functional theory studies. In the present study we use electronic structure calculations to evaluate the binding energies of $F_{n}V_{m}$ clusters and $V_{n}$ clusters. The significant binding energies of the $V_{n}$ clusters reveals that the concentration of the large $F_{n}V_{m}$ clusters (n ≥4, m ≥1) will be limited compared to the $V_{n}$ clusters or even smaller clusters.