E' centers and nitrogen-related defects in SiO₂ films

We have observed an electron paramagnetic resonance signal corresponding to a neutral fourfold coordinated nitrogen in plasma-enhanced chemical vapor deposited SiO2 films fabricated under certain conditions. The same films contain E' centers (positive oxygen vacancies) in an equal quantity. Our data support a model in which these two paramagnetic centers are created simultaneously by an electron transfer, starting from a positive fourfold nitrogen and a neutral oxygen vacancy. This model allows an earlier observation of an apparently neutral E' variant to be interpreted as a normal positive E' plus a nitrogen center to conserve charge.