Dimer Reconstruction at Metal-Silicide/Silicon Interfaces: A First-Principles Study

By employing first-principles total-energy calculations we studied the atomic and chemical structure of NiSi2/Si(001) and CoSi2/Si(001) interfaces that are of great importance in understanding electronic properties, such as the Schottky-barrier height, of metal-silicide/silicon junctions. We found a new structural model that is more stable than previously proposed models of interface structures and well explains existing experimental data. The new interface model consists of sevenfold-coordinated interfacial metals and a 2×1 periodic array of interfacial Si dimers, similar to the Si(001) 2×1 surface reconstruction, reducing the number of dangling bonds.