The electronic properties of the (100) Si/SiO2 interfacial defect, Pb1, were controversial. Electron spin resonance measurements were presented that demonstrated that the Pb1 defects had levels in the Si band-gap, that the Pb1 correlation energy was significantly smaller than that of the Pb1 defect and that the Pb1 levels were skewed toward the lower part of the Si band gap.

Density of States of Pb1 Si/SiO2 Interface Trap Centers. J.P.Campbell, P.M.Lenahan: Applied Physics Letters, 2002, 80[11], 1945-7