Radiation effect on metal-contaminated Si diodes

Results are presented from a study of the degradation of the electrical performance of Fe-contaminated n(+)p Si diodes subjected to a 220-MeV carbon irradiation. The reverse current of the diodes increase after irradiation, while the capacitance decrease. The area and the peripheral components of the leakage current were extracted from diodes with different area-to-perimeter ratios. Both the generation and the recombination lifetimes calculated from current-voltage and the capacitance-voltage characteristics also decreased. The deep levels induced in the Si substrate by irradiation were mainly responsible for the degradation of diode performance. The radiation damage was also compared to the results for 1-MeV electrons and 1-MeV fast neutrons. The performance degradation for carbon irradiation is three orders of magnitude larger than that for electron irradiation The differences in the radiation damage are explained by the differences in the number of knock-on atoms and the nonionizing energy loss (NIEL), which is attributed to the difference in the masses and to the possibility of nuclear collisions with target Si atoms.