An investigation was made, of the origin of the photoluminescence W-band in ion-implanted samples, by studying the temperature evolution and the depth profiles of related defects. The evolution of the photoluminescence spectra, which was induced by post-implantation annealing, was correlated with the transition of small interstitial clusters to extended {311}-defects in self-ion implanted material. An increase in W-band intensity, after step-by-step removal of the damaged layer, ruled out the involvement of vacancy-related defects in the formation of the W-center and established that migrated and clustered interstitials gave rise to an intense W-band. The annealing behavior, and the thermally activated growth of the W center, suggested the involvement of small interstitial clusters which were larger than the di-interstitial. It was argued that the W-center consisted of tri-interstitial clusters of Si.

Evidence for Small Interstitial Clusters as the Origin of Photoluminescence W Band in Ion-Implanted Silicon. P.K.Giri, S.Coffa, E.Rimini: Applied Physics Letters, 2001, 78[3], 291-3