First-principles study of Ge dangling bonds in GeO_2 and correlation with electron spin resonance at Ge/GeO_2 interfaces

摘要

The g-tensors of dangling bonds at defective Ge atoms in GeO_2 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/GeO_2 interfaces, recently observed by electron spin resonance (ESR) experiments, we tentatively identify this defect as a Ge_2OsGe~* center, i.e., a dangling bond on a Ge atom backbonded to two Ge atoms and one O atom, likely present near the Ge/GeO_2 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.