Recombination of nonequilibrium charge carriers in heavy ion tracks in silicon

The charge carrier losses λf during irradiation of silicon pn-junction detectors with heavy ions (fission fragments of 252Cf) have been investigated regarding the dependence on the electric field strength F. The function λ1(F) was obtained experimentally in the logarithmic form λ1 = γ × in(1 /F) and compared to a model prediction describing the recombination at defects induced inside the track of penetrating heavy ions. The obtained coefficient γ = (40.5±6.1) × 10−3 does not depend on the electric field strength and allows one to determine the effective cross section σ = 2.5 × 10−14 cm2 of charge carrier trapping at fission fragment induced defects in silicon.