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Annealing studies were performed to investigate the recovery of both the carrier concentration and lifetime in silicon following room temperature irradiation with 10-MeV electrons. Both n- and p-type material containing the more common dopants and varying amounts of oxygen were employed to evaluate the effect of these impurities on the annealing behavior. The recovery of carriers in n-type material was found to depend very strongly upon oxygen. A well-defined recovery stage was observed at intermediate temperature (~110Â° to 180Â° C) in oxygen-free samples but not in pulled material. The position of the stage appeared to depend upon the dopant, and for this reason it is attributed to the breakup of donor-vacancy complexes. In contrast, no appreciable carrier recovery was obtained in p-type material after anneals up to 253Â° C, regardless of the dopant or the oxygen content. Annealing of lifetime changes was particularly interesting. A pronounced annealing stage at ~225Â° C was observed in all but one of the n-type samples regardless of the oxygen content and in p-type samples containing oxygen. The detailed behavior due to this stage was dependent upon the radiation dose. Oxygen-free p-type samples exhibited completely different annealing behavior. A prominent reverse annealing stage at~144Â° C was observed in four of these samples and no subsequent positive recovery was observed up to 283Â° C.