The Pb center at (111)Si/SiO2 interfaces was studied, using electron-nuclear double-resonance spectroscopy, by taking advantage of the high specific interfacial area of oxidized porous Si samples. It was found that the spectrum consisted of only 2 structure-less lines at the Larmor frequencies of 1H and 19F. No hyperfine interaction with 29Si could be detected. The Pb-1H and Pb-19F distances were estimated, in the dipole-dipole approximation, to be equal to about 1.3nm. This corresponded to the average Pb center separation. The intensity ratio of the 1H and 19F electron-nuclear double-resonance spectroscopic lines was stable with respect to high-temperature vacuum annealing and H treatments. Quantitative electron paramagnetic resonance measurements of the central hyperfine structure intensity confirmed the attribution of the Pb center to the Si dangling-bond defect.

V.J.Bratus, S.S.Ishchenko, S.M.Okulov, I.P.Vorona, H.J.Von Bardeleben, M.Schoisswohl: Physical Review B, 1994, 50[20], 15449-52