Charge state of paramagnetic E´ centre in thermal SiO2layers on silicon

Comparison between the densities of positive charge and paramagnetic E´ centres (O 3 Si defects) generated in thermal SiO 2 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 Si-H fragment in the SiO 2 network, which is converted into an E´ centre by radiation-induced hydrogen cracking.