Positron annihilation studies of high dose Sb implanted silicon

The formation and evolution of vacancies and precipitates created by implantation of 60 keV, 2 × 1016 cm−2 Sb+ in pre-amorphized (0 0 1) Cz-Si is studied using the Doppler broadening (DB) and two-dimensional angular correlation of annihilation radiation (2D-ACAR) positron beam techniques. After implantation, samples were laser annealed (LTA) and subsequently thermal annealed at temperatures ranging from 400 to 1000 °C. Implantation-induced vacancy-type defects were detected up to a depth of 280 nm. After LTA, positron annihilation related to both Sb and remaining defects is observed in the first 100 nm below the surface. The deeper region only shows positron trapping at vacancy-type defects with strong reduced concentration. Complete removal is obtained after 600 °C anneal. At this temperature, the positron data for the upper region reveals trapping at Sb and Si sites only. With increasing annealing time (at 600 °C) or increasing temperature (up to 1000 °C) positron annihilation at Sb-sites associated with neighboring vacancies becomes apparent. Results are correlated with the observed Sb electrical deactivation above 600 °C, the shift from small Sb aggregates to precipitates and out-diffusion of Sb from the implantation region at higher temperatures.