A new Si di-interstitial model was based upon Si-P6 electron paramagnetic resonance spectra from neutron-, proton- or ion-implanted samples. Two Si interstitials were assumed to lie in the {100} plane, at a position which was considerably off from 2 nearby tetrahedral interstitial sites, and share one Si lattice atom. The di-interstitial disappeared upon annealing at 170C and could form <110> interstitial chains which were considered to be a component of the {311} extended defects which were frequently observed in ion-implanted Si.

Silicon di-interstitial in ion-implanted silicon Y.H.Lee: Applied Physics Letters, 1998, 73[8], 1119-24