Charge state of paramagnetic E′ centre in thermal SiO2 layers on silicon

Comparison between the densities of positive charge and paramagnetic E' centres (O(3)drop Si-. defects) generated in thermal SiO2 layers on Si by 10 eV photons at different electric field strengths in the oxide demonstrates that the paramagnetic states cannot be associated with positively charged centres, i.e., the E' centre is neutral. The variation in E' density results from the balance between activation by irradiation and passivation with radiolytic hydrogen. Therefore, the neutral diamagnetic state of the defect is ascribed to the O(3)drop Si-H fragment in the SiO2 network, which is converted into an E' centre by radiation-induced hydrogen cracking.