Initial stages of erbium disilicide formation on Si(0 0 1)

The initial stages of ErSi2 formation on Si(0 0 1) are investigated by scanning tunneling microscopy and low energy electron diffraction. At sub-monolayer coverages two Er-induced superstructures are observed, where Er dimers are replacing the Si dimers. In the c(4×2) phase Er dimers alternate with Si dimers both along and perpendicular to the Si dimer row direction. The (2×3) phase, which evolves naturally from the c(4×2) phase with increasing coverage, consists of two adjacent chains of Er dimers and can be regarded as a precursor of the strain-field-controlled ErSi2 nanowire growth.