First-principles calculation of the band offset at ${\mathrm{B}\mathrm{a}\mathrm{O}/\mathrm{B}\mathrm{a}\mathrm{T}\mathrm{i}\mathrm{O}}_3$ and ${\mathrm{S}\mathrm{r}\mathrm{O}/\mathrm{S}\mathrm{r}\mathrm{T}\mathrm{i}\mathrm{O}}_3$ interfaces

We report first-principles density-functional pseudopotential calculations on the atomic structures, electronic properties, and band offsets of ${\mathrm{B}\mathrm{a}\mathrm{O}/\mathrm{B}\mathrm{a}\mathrm{T}\mathrm{i}\mathrm{O}}_3$ and ${\mathrm{S}\mathrm{r}\mathrm{O}/\mathrm{S}\mathrm{r}\mathrm{T}\mathrm{i}\mathrm{O}}_3$ 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, ${\mathrm{SrTiO}}_3/\mathrm{Pt},$ and ${\mathrm{BaTiO}}_3/{\mathrm{SrRuO}}_3$ interfaces we extrapolate the band alignments along two gate stacks of technological interest: ${\mathrm{S}\mathrm{i}/\mathrm{S}\mathrm{r}\mathrm{O}/\mathrm{S}\mathrm{r}\mathrm{T}\mathrm{i}\mathrm{O}}_3/\mathrm{Pt}$ and ${\mathrm{S}\mathrm{i}/\mathrm{B}\mathrm{a}\mathrm{O}/\mathrm{B}\mathrm{a}\mathrm{T}\mathrm{i}\mathrm{O}}_3/{\mathrm{SrRuO}}_3$ heterostructures.