The transition, from small interstitial clusters to {311} defects, was studied in ion-implanted samples. Wafers of Czochralski-type material were implanted with 1.2MeV Si ions to fluences ranging from 1012 to 5 x 1013/cm2, and were annealed at 600 to 750C for times of up to 15h. Photoluminescence and transmission electron microscopic techniques revealed the transformation of small interstitial clusters, which were formed via the agglomeration of excess interstitials that were introduced by the beam, into {311} defects. It was found that the latter formed only at fluences above 1013/cm2, and at temperatures above 600C. When {311} defects were observed using transmission electron microscopy, the luminescence spectrum was dominated by a sharp signal at 1376nm. This was related to optical transitions which occurred at, or close to, these defects. At lower temperatures or lower fluences, no extended defects were observed using transmission electron microscopy while the luminescence spectrum contained 2 broad signatures that arose from carrier recombination at interstitial clusters. The data strongly suggested that severe structural transformations occurred during the change from small interstitial clusters to extended {311) defects.

Transition from Small Interstitial Clusters to Extended {311} Defects in Ion-Implanted Si S.Coffa, S.Libertino, C.Spinella: Applied Physics Letters, 2000, 76[3], 321-3