The effect of a point defect excess, vacancies, or, respectively, interstitials, on the deactivation kinetics of As in Si was verified on silicon on insulator (SOI) substrates uniformly doped at concentrations in the range 1.8–7×1020 cm−3. SOI samples can provide more accurate carrier density measurements, moreover the buried oxide layer can prevent recombination of excess vacancies with the interstitials near the projected range. A dose of 5×1015 cm−2 Si+ ions was implanted at 100 keV to obtain interstitials supersaturation (Iex), while the same Si+ dose, at an energy of 2 MeV, was used to generate an excess of vacancies (Vex). These specimens were isothermally heated at different temperatures and their annealing behavior was compared with the one of reference undamaged samples of the same composition, but without point defect excess. Our results indicate that neither the excess of interstitials nor the one of vacancies appreciably affect the deactivation rate. Once the implantation damage has annealed out, the samples with point defect excess are found in the same situation of the reference ones, and the subsequent deactivation kinetics results coincident. © 2002 American Institute of Physics.