Minority Carrier Recombination in Neutron Irradiated Silicon

Abstract

Measurements are reported which provide extensive data on the resistivity, temperature, and injection level dependences of the minority carrier lifetime in neutron irradiated p- and n-type silicon. The lifetime damage constants are observed to be quite dependent on the injected minority carrier density, in both conductivity types, over the temperature range from 76°K to 300°K. The low injection level damage constants have been measured and found to be dependent on material resistivity in p-type silicon, but only slightly dependent on resistivity in n-type silicon. The results of the experimental studies are compared to the predictions of two alternate models for recombination at defect clusters. For defect clusters of approximately 250 A radius, as expected from range calculations, these comparisons indicate that each contains a relatively small number of deep defects (30 - 40). The defects are individually characterized by a deep donor level near Ev + 0.35 eV and a deep acceptor level near Ec - 0.50 eV. Since these levels correspond approximately to the known energy levels of the silicon divacancy, it is suggested that the divacancy may be the active recombination center within the defect clusters.