Recombination in Gamma-Irradiated Silicon

Abstract

The lifetimes of excess carriers in phosphorus-doped, float-zoned silicon were measured before and after irradiation by cobalt-60 gamma rays. Recombination in the samples prior to irradiation was dominated by a donor-like recombination center located 0.13 eV above the valence band. After irradiation, two recombination centers were found in the samples: one located at Ec-0.17 eV and the other at Ec-0.40 eV. The center at Ec-0.17 eV can be identified with the oxygen-vacancy defect (Si-A center), but no positive identification of the Ec-0.40 eV center can be made. By assuming that the Ec-0.40 eV center is the phosphorus-vacancy complex, the hole capture cross section of the center was estimated as 9 × 10−14 cm2.