The aim of this paper is to demonstrate, for the first time, the possible e
xistence of planar point defect silicon self-interstitials in the {311} pla
ne. The results offer a plausible explanation as to why self-interstitials
aggregate to form {311} defect clusters during ion implantation. These inte
rstitials do not leave any dangling bonds and can be considered to be "exte
nded," due to spread out perturbations.