First-principles calculation of the band offset at BaO/BaTiO$_3$ and   SrO/SrTiO$_3$ interfaces
  We report first-principles density-functional pseudopotential calculations on the atomic structures, electronic properties, and band offsets of BaO/BaTiO$_3$ and SrO/SrTiO$_3$ nanosized heterojunctions grown on top of a silicon substrate. The density of states at the junction does not reveal any electronic induced interface states. A dominant perovskite character is found at the interface layer. The tunability of the band offset with the strain conditions imposed by the substrate is studied. Using previously reported theoretical data available for Si/SrO, Si/BaO and BaTiO$_{3}$/SrRuO$_{3}$ interfaces we extrapolate a value for the band alignments along the whole gate stacks of technological interest: Si/SrO/SrTiO$_3$ and Si/BaO/BaTiO$_3$/SrRuO$_3$ heterostructures. 
Javier Junquera (1), Magali Zimmer (1), Pablo Ordejon (2), and   Philippe Ghosez (1) ((1) Universite de Liege, Belgium, (2) ...