Annealing of 10 MeV Electron Damage in Silicon

Abstract

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 (~110° to 180° 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 253° C, regardless of the dopant or the oxygen content. Annealing of lifetime changes was particularly interesting. A pronounced annealing stage at ~225° 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~144° C was observed in four of these samples and no subsequent positive recovery was observed up to 283° C.