Radiation effect on metal-contaminated Si diodes

Results are presented from a study of the degradation of the electrical per formance of Fe-contaminated n(+)p Si diodes subjected to a 220-MeV carbon i rradiation. The reverse current of the diodes increase after irradiation, w hile the capacitance decrease. The area and the peripheral components of th e leakage current were extracted from diodes with different area-to-perimet er ratios. Both the generation and the recombination lifetimes calculated f rom current-voltage and the capacitance-voltage characteristics also decrea sed. 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 neutro ns. The performance degradation for carbon irradiation is three orders of m agnitude larger than that for electron irradiation The differences in the r adiation damage are explained by the differences in the number of knock-on atoms and the nonionizing energy loss (NIEL), which is attributed to the di fference in the masses and to the possibility of nuclear collisions with ta rget Si atoms.