Study on defects of solar cell silicon irradiated with 1 MeV electrons by positron annihilation

In order to obtain information on the degradation of solar cells in artific ial satellites as a result of cosmic ray radiations, positron annihilation lifetime experiments were performed for B-doped p-type Czochralski (CZ) sil icon wafers irradiated at room temperature with 1 MeV electrons with fluenc es between 10(14) and 10(17) e/cm(2). Positron lifetime measurements were d one at 100 K to improve the trapping rates of positrons with defects. The m ean lifetime of irradiated Si was shorter than that of unirradiated Si. We found that short lifetime defects (approximately 100 ps) existed, which cou ld be associated with complexes of Si with interstitial oxygen atoms, doped B and vacancies resulting from irradiation. Lifetime components longer tha n those of the bulk accounted for the formation of thermal donors and divac ancies.