Eγ′ centers induced by γ irradiation in sol-gel synthesized oxygen deficient amorphous silicon dioxide

The effects of room temperature gamma-ray irradiation up to a dose of similar to 1300 kGy are investigated by Electron paramagnetic resonance (EPR) measurements in amorphous silicon dioxide (a-SiO2) produced by a sol-gel synthesis method that introduces O Si-Si O oxygen deficiency. We have found that exposure to radiation generates the E-gamma' center with the same spectral features found in high purity commercial a-SiO2. The maximum concentration of defects induced in this sol-gel material indicates that its resistance to radiation is comparable to that of synthetic fused a-SiO2. The concentration of E-gamma' center increases with irradiation, featuring a sublinear dose dependence up to the highest investigated dose and showing no saturation effects. This defect generation process suggests that the chemically induced precursor influences the mechanisms of E-gamma' center generation. (c) 2007 Elsevier B.V. All rights reserved.