Template structure at the silicon/amorphous-silicide interface

Surface x-ray diffraction was used to monitor the reaction of Ni on Si(111) at room temperature. Intensity oscillations during deposition signify that a layerwise reaction occurs for the first 30 Å of metal deposited, forming a silicide overlayer with stoichiometry Ni2Si. Structural analysis of the interfacial layers detects an epitaxial and commensurate phase, Ni2Si- θ, with long range order imposed by the substrate but with very large local atomic displacements. This epitaxial structure remains at the interface as amorphous silicide forms above it.