Large fluorine-vacancy clusters in Si and their capture efficiency for self-interstitials

摘要

Based on ab initio density-functional energetics for saturated (n=2m+2) fluorine-vacancy clusters F_nV_m for m up to 4, the authors set up a model showing that (a) fluorine-vacancy (F-V) aggregates in Si can form in any size and concentration for sufficient concentrations of incorporated (e.g., implanted) F, and (b) the F to V ratio in F-V complexes (i.e., the inverse capture efficiency of self-interstitials) is an ensemble average over many cluster sizes. It ranges between 4 and 2, with typical values of 2.2-2.5, consistent with recent experimental estimates.