Impurity gettering to secondary defects created by MeV ion implantation in silicon

Impurities in MeV-implanted and annealed silicon may be trapped at interstitial defects near the projected ion range, $Rp,$ and also at vacancy-related defects at approximately $Rp/2.$ We have investigated the temperature dependence of impurity trapping at these secondary defects, which were preformed by annealing at $900 °C.$ The binding energies of Fe, Ni, and Cu are greater at the vacancy-related defects than at extrinsic dislocation loops. During subsequent processing at temperatures up to $900 °C,$ the amount of these impurities trapped at $Rp/2$ increases with decreasing temperature while the amount trapped at $Rp$ decreases, with most of the trapped metals located at $Rp/2$ in samples processed at temperatures $≲ 700 °C.$ However, intrinsic oxygen is trapped at both types of defects; this appears to have little effect on the trapping of metallic impurities at extrinsic dislocations, but may inhibit or completely suppress the trapping at vacancy-related defects.