NEW INTERFACE STRUCTURE FOR A-TYPE COSI2 SI(111)/

A new model of a CoSi2/Si(111) interface structure has been generated using images produced by Z-contrast scanning transmission electron mic roscopy. The images indicate that the top and bottom interfaces betwee n the type-A buried CoSi, layer and Si(111) both have eightfold coordi nated Co atoms. This is accomplished by converting the one interface s tructure from sevenfold to eightfold coordination by locating a twinne d layer of Si at the interface. The preference for this interface over the sevenfold type-A structure is in agreement with theoretical predi ctions.