New Silicide Interface Model from Structural Energy Calculations

Local-density-functional calculations have been employed to study the energies of the epitaxial (111) interfaces ${\mathrm{S}\mathrm{i}-\mathrm{N}\mathrm{i}\mathrm{S}\mathrm{i}}_2$ and ${\mathrm{S}\mathrm{i}-\mathrm{C}\mathrm{o}\mathrm{S}\mathrm{i}}_2$. For ${\mathrm{NiSi}}_2$, the widely accepted interface structure with sevenfold-coordinated Ni has the lowest energy. For ${\mathrm{CoSi}}_2$, however, a new structure with eightfold-coordinated Co has the lowest energy, and the widely discussed fivefold structure is seen to be extremely unfavorable.