Vacancy-type defects created by single-energy implantation of Czochralski-grown single-crystal silicon by 4MeV silicon ions at doses of 1012 and 1013/cm2 were compared with those created by an energy chain of implants of 0.4, 0.9, 1.5, 2.2 and 4MeV ions, each at one-fifth of the single-energy dose. Measurements were taken for as-implanted samples and after annealing at up to 600C. In contrast to the expectation that a more uniform depth distribution of interstitials and vacancies would lead to a more efficient recombination and consequently fewer surviving vacancies, vacancy-related damage survived in the chain-implanted samples to higher temperatures, before almost complete annealing at 600C. It was therefore concluded that it was the absolute initial monovacancy concentration, rather than any initial separation of vacancy- and interstitial-rich regions, that determines the probability of survival as divacancies, and that there exists a threshold divacancy concentration of 1-2 x 1018/cm3 for clustering at 400 to 500C.

Vacancy-Type Defects Created by Single-Shot and Chain Ion Implantation of Silicon. P.G.Coleman, C.J.Edwardson, A.P.Knights, R.M.Gwilliam: New Journal of Physics, 2012, 14[2], 025007