Theoretical study of Ge dangling bonds in GeO 2 and correlation with ESR results at Ge/GeO 2 interfaces

The g-tensors of dangling bonds at defective Ge atoms in GeO2 are computed using density functional theory. The isotropic g-values of these defects are found to increase with the number of Ge backbonds. By comparing these calculations with the isotropic g-value of a Ge-related defect at Ge/GeO2 interfaces, recently observed by electron spin resonance and electrically detected magnetic resonance experiments, we tentatively identify this defect as a Ge2O Ge-center dot center, i.e. a dangling bond on a Ge atom backbonded to two Ge atoms and one O atom, likely present near the Ge/GeO2 interface. The interaction of this defect with molecular hydrogen is investigated using first-principles molecular dynamics simulations. Our simulations predict that the Ge dangling bond can be hardly passivated by H-2 molecules, in agreement with the electron spin resonance study.