Dipolar interactions between unpaired Si bonds at the (111)Si/SiO2 interface

Direct experimental evidence for the dipolar interactions within the two-dimensional Pb defect system at the Si/SiO2 interface is provided by the observation of anisotropy in the electron spin resonance spectra. This observation was enabled through distinct interface degradation by post-oxidation annealing in H2, leading to enhanced Pb density. The data are interpreted within the framework of a computational model based on the magnetostatic approximation of the local field. The results suggest Pb defects to exhibit a self-avoiding behaviour and confirm their occurrence as related to the release of interface stress.