he point defects of Pb and E’in two kinds of Si-SiO2 formed by different techllological process

before and after irradistion with different dosage and bias field

have been examined using election spin resonance （ESR）. The experimental results show that there are Pb defects in both kinds of Si-SiO2 no matter whether they are irradiated

and the radiation of 60Co can generate more Pb defects in the Si-SiO2 systems. In the first kind of Si-SiO2 the E’ defects can be observed after irradiation with positive bias field

while with free field these defects appear only when the irradiation dosage is as high as 50 kGy（Si）. But there are not any E’ in the second kind of Si-SiO2 even if they are irradiated. Besides

the ΔH（peak to peak） of Ph and E’ in the ESR spectya indicates that Ph is referred to a slow relaxation defect but E’ to a fast relaxation defect. Finally

the experimental results are qualitatively explained.