Ge dangling bonds at the (100)Ge/GeO2 interface and the viscoelastic properties of GeO2

Abstract

The electronic energy band structure of a (100)Ge/GeO2 interface with a Ge3≡Ge• center (Ge dangling bond) is calculated using the density functional theory. The defect level associated with this dangling bond is found to lie near the middle of the Ge band gap. Consequently, the Ge dangling bond at this interface should be paramagnetic when the Fermi level is near the midgap, and it should thus be observed by electron spin resonance (ESR), which appears to be in contradiction with the results reported by [Afanas’ev et al., Appl. Phys. Lett. 87, 032107 (2005)]. We point out that the density of Ge3≡Ge• centers at the (100)Ge/GeO2 interface is possibly at/below the ESR detection limit due to the viscoelastic properties of GeO2, owing to a better stress relaxation at/near the interface, compared to its silicon counterpart.