It was recalled that vacancies, interstitials and Frenkel pairs were considered to be the basic point defects in Si. This point of view was questioned here by presenting density functional calculations which showed that there was a stable point defect in Si that had 4-fold coordination and was lower in energy than the traditional defects.

A Fourfold Coordinated Point Defect in Silicon. S.Goedecker, T.Deutsch, L.Billard: Physical Review Letters, 2002, 88[23], 235501 (4pp)