Positron annihilation lifetime experiments were performed on B-doped p-type Czochralski wafers which were irradiated with 1MeV electrons, at room temperature, to fluences of between 1014 and 1017/cm2. Positron lifetime measurements were made at 100K in order to improve the trapping rates of positrons by defects. The mean lifetime in irradiated material was shorter than that in non-irradiated material. It was found that short-lifetime defects (100ps) existed which could be associated with a complex of Si with interstitial O atoms, doped B and vacancies resulting from irradiation. Lifetime components which were longer than that of the bulk were attributed to the formation of thermal donors and divacancies.

Study of Defects in Solar-Cell Silicon Irradiated with 1MeV Electrons by Positron Annihilation. T.Tamano, F.Hori, R.Oshima, T.Hisamatsu: Japanese Journal of Applied Physics - 1, 2000, 39[8], 4693-8