A comparison was made of the densities of positive charge and paramagnetic E' centres (O3=Si▪) that were generated in thermal SiO2 layers on Si by 10eV photons at various electric field strengths. This demonstrated that the paramagnetic states could not be associated with positively charged centres. That is, the E' centre was neutral. The variation in E' density resulted from a balance between activation by irradiation and passivation by radiolytic H. Therefore, the neutral diamagnetic state of the defect was attributed to the O3=Si-H fragment in the SiO2 network. This was converted into an E' centre by radiation-induced H-cracking.

Charge State of Paramagnetic E' Centre in Thermal SiO2 Layers on Silicon. V.V.Afanasev, A.Stesmans: Journal of Physics - Condensed Matter, 2000, 12[10], 2285-90