Interface reconstruction of MSi2/Si(001) (M=Co,Ni) from first principles

First-principles calculations based on density-functional theory and generalized gradient approximation were performed to study the interface structures of epitaxial NiSi2 and CoSi2 on a Si(001) substrate. A sevenfold-Z model with zigzag Si-dimer rows in the interface layer is proposed. The model is energetically comparable to an established sevenfold-R model and they could coexist in both CoSi2/Si and NiSi2/Si structures, leading possibly to degradation of the interface quality of the silicide/silicon heterostructure.