Interstitial aggregates and a new model for the I1/W optical centre in silicon

Abstract First principles local-density-functional (LDF) theory is employed to investigate the properties of di-interstitial (I2), tri-interstitial (I3) and tetra-interstitial (I4) structures in silicon. We show that a tri-interstitial defect can account for many of the fundamental properties of the I1/W-optical centre which is observed in irradiated, annealed silicon.