Bonding, Energies, and Band Offsets of $\mathrm{S}\mathrm{i}\mathrm{\text{−}}{\mathrm{Z}\mathrm{r}\mathrm{O}}_2$ and ${\mathrm{H}\mathrm{f}\mathrm{O}}_2$ Gate Oxide Interfaces

New oxides with high dielectric constant are required for gate oxides. ${\mathrm{Z}\mathrm{r}\mathrm{O}}_2$ is a typical example with ionic bonding. We give the rules for bonding at interfaces between Si and ionic oxides, to satisfy valence requirements and give an insulating interface. Total energies and band offsets are calculated for various $(100)\mathrm{S}\mathrm{i}:{\mathrm{Z}\mathrm{r}\mathrm{O}}_2$ and ${\mathrm{H}\mathrm{f}\mathrm{O}}_2$ interface structures. The oxygen-terminated interface is found to be favored for devices, because it has no gap states and has a band offset which is rather independent of interfacial bonding.