New interface structure for A-type CoSi sub 2 /Si(111)

A new model of a CoSi sub 2 /Si(111) interface structure has been generated using images produced by Z-contrast scanning transmission electron microscopy. The images indicate that the top and bottom interfaces between the type-A buried CoSi sub 2 layer and Si(111) both have eightfold coordinated Co atoms. This is accomplished by converting the one interface structure from sevenfold to eightfold coordination by locating a twinned layer of Si at the interface. The preference for this interface over the sevenfold type-A structure is in agreement with theoretical predictions.