The electronic and structural properties of the Ge/GeO2 interface are addressed through a density functional simulation scheme which includes the use of hybrid functionals for achieving accurate band gaps, band offsets and defect levels. The present work discusses the germanium dangling bond levels, the thermodynamics of GeOx, the stability of the oxygen vacancy across Ge/HfO2 interfaces, the atomic structure of GeOx, electron and hole trapping in GeOx, and the band alignment at the Ge/GeO2 interface. (C) 2011 Elsevier B.V. All rights reserved.