New Silicide Interface Model from Structural Energy Calculations

Local-density-functional calculations have been employed to study the energies of the epitaxial (111) interfaces Si-NiSi₂ and Si-CoSi₂. For NiSi₂, the widely accepted interface structure with sevenfold-coordinated Ni has the lowest energy. For CoSi₂, however, a new structure with eightfold-coordinated Co has the lowest energy, and the widely discussed fivefold structure is seen to be extremely unfavorable.