INTERACTION OF ALPHA-RADIATION INDUCED DEFECTS WITH PD-RELATED DEEP LEVELS IN SILICON

Results of a detailed deep level transient spectroscopy study of Pd-do ped p+ n Si diodes irradiate with 5.48 MeV alpha particles are present ed, which also include investigations of isochronal annealing behavior of the deep level spectra up to a temperature of 350-400-degrees-C. A n extended comparison with results obtained on reference samples as we ll as with previously published results of deep level studies on Pd-do ped samples (unirradiated) and on undoped alpha-irradiated samples pro vides valuable information, since the same starting material is used i n all these studies. It is observed that, in general, the Pd-related d eep levels increase in concentration upon irradiation at the expense o f alpha-radiation-induced levels. In particular, the A center sharply decreases in concentration upon post-irradiation annealing with a corr esponding increase in the concentration of the dominant Pd-related lev el. The results also show that, contrary to the previously held belief , two well-known Pd-related levels at E(c)-0.37 eV and E(c)-0.59 eV ar e not states of the same defect and an off-center/on-center substituti onal Pd-vacancy model for the defects corresponding to E(c)-0.18 eV an d E(c)-0.22 eV Pd-related levels cannot explain new data presented her e. In the reference (undoped, heat treated) samples, a few levels are observed after alpha-irradiation or post-irradiation annealing which w ere not detected in the untreated diodes, pointing to their relationsh ip to quenched-in defects. A new annealed-in hole level H(alpha-Pd) at E(upsilon)+0.27 eV is observed which seems to be a complex of Pd with some alpha-irradiation-induced defect.