Structure and Electronic Properties of Epitaxial Silicon-Silicide Interfaces

The fluorite structure silicides CoSi sub 2 and NiSi sub 2 form the most abrupt and atomically perfect metal-semiconductor interfaces presently known. As such, they provide an ideal meeting ground for detailed microscopic theory and experiment. In this talk, I will discuss four topics in this area. The first is the application of local density functional total energy calculations to questions of silicide interface growth and structure. Direct growth of a silicide-like structure for the few monolayers of Ni is shown to be strongly favored over a proposed interstitial precusor phase. Different structures are found for (111) CoSi sub 2 and NiSi sub 2 interfaces, consistent with experiment. However, the coordination of the interface Co atom is found to be different from the generally accepted model, calling for new experiments.