AB-INITIO STRUCTURAL STUDY OF THE SILICON/NICKEL DISILICIDE INTERFACES

Using our recently developed ab initio schemes for generating optimally smooth pseudopotentials, we have carried out the first fully relaxed structural study of a silicon/transition-metal-silicide interface, NiSi2/Si(111), by allowing the atoms to be fully mobile in the direction perpendicular to the interface. We found that the contraction of the silicide triple layer immediately adjacent to the interface is responsible for most of the interface relaxation. This is in disagreement with the assumption that the relaxation occurs primarily at the interface Si-Si bond. Such an assumption has been used to interpret the experimental results as well as being used in most of the electronic-structure calculations and may be responsible for the disagreement between the calculated and measured results for the Schottky barrier heights. We also confirm that the type-A interface is more energetically favored than type B, while the type-B interface relaxes more than type A.