Band offsets of SrTiO$_3$ thin films grown on Si

SrTiO$_3$ is a promising material to replace SiO$_2$ as the gate dielectric in metal-oxide-semiconductor field-effect transistors (MOS-FETs). The advantage of SrTiO$_3$ is its large dielectric constant: an order of magnitude greater than other promising oxides. However, the negligible conduction band offset found experimentally for heterostructures of SrTiO$_3$ (001) grown on Si (001) limits the usefulness of SrTiO$_3$ in devices because of leakage current. Here we present first-principles calculations on Si/SrTiO$_3$ heterostructures and investigate ways to modify the band offsets. Experimentally motivated structures are considered, and the effects of dopants and defects on the electronic structure are quantified.