Band Offsets at Semiconductor-Oxide Interfaces from Hybrid Density-Functional Calculations

Abstract

Band offsets at semiconductor-oxide interfaces are determined through a scheme based on hybrid density functionals, which incorporate a fraction $\ensuremath{\alpha}$ of Hartree-Fock exchange. For each bulk component, the fraction $\ensuremath{\alpha}$ is tuned to reproduce the experimental band gap, and the conduction and valence band edges are then located with respect to a reference level. The lineup of the bulk reference levels is determined through an interface calculation, and shown to be almost independent of the fraction $\ensuremath{\alpha}$. Application of this scheme to the $\mathrm{Si}\mathrm{\text{\ensuremath{-}}}{\mathrm{SiO}}_{2}$, $\mathrm{SiC}\mathrm{\text{\ensuremath{-}}}{\mathrm{SiO}}_{2}$, and $\mathrm{Si}\mathrm{\text{\ensuremath{-}}}{\mathrm{HfO}}_{2}$ interfaces yields excellent agreement with experiment.