Electron paramagnetic resonance (EPR) measurements were employed to observe the dominant defect at the thermally grown (1 1 1) Si-SiO(2) interface, namely the P(b) center, of samples with oxides grown at moderate temperatures. The presence of boron diffusion leads to an increase of the P(b) density by a factor of similar to 1.6 to 1.8, significantly less than previously reported for higher temperature oxides. The P(b) density for samples with similar emitter sheet resistances but different (by a factor of 4) boron surface concentrations were similar, suggesting that the increase in P(b) concentration following is primarily determined by the total boron dose. Investigations of the stability of the passivation of boron diffused, oxide passivation emitters strongly suggest that degradation is the result of the permeability of SiO(2) to moisture, which can be prevented through the addition of a moisture barrier. (C) 2010 Elsevier B. V. All rights reserved.