Of the many point defects detected by electron paramagnetic resonance (EPR) in SiO2 films, two appear to be associated with high temperature dry nitrogen treatment, one at g=2.0017 (Eδ') and one at g=2.0027. Earlier work suggests that the former is a multiple oxygen vacancy center, and the latter, we postulate, is a an impurity-related variant of the EX center [1,2]. The model for the 2.0027 center is based on its chemical properties which closely reflect those of the EX center. Invocation of impurity effects arises from the spectroscopic similarities between our center and previously observed centers in oxide films and Si surfaces. The 2.0027 center is compared with Eδ' by contrasting the location, annealing rate at 200° C, and effect of ambient gas.
