Structure, energetics, and extrinsic levels of small self-interstitial clusters in silicon

Native defects in Si are of obvious importance in microelectronic device processing. Self-interstitials in particular are known to mediate, in many cases, anomalous impurity diffusion. Here we study the energetics and electronic structure of single, double, and triple self-interstitial clusters in crystalline Si in various charge states and geometries, providing extrinsic levels and binding-association-dissociation energies. We discuss the comparison of our results with some experimental data on self-implanted Si. We also reconsider the migration energetics of single interstitials in the light of recent experiments, and point out the possible role of cluster nucleation in the electrical activation of acceptor-implanted samples.