Surface structures of erbium silicide ultra-thin films formed by solid phase epitaxy on Si(1 0 0)

The surface structures of thin erbium silicide layers formed on Si(1 0 0) substrate by solid phase epitaxy are studied by using the in situ high energy electron diffraction, low energy electron diffraction, Auger electron spectroscopy, scanning tunneling microscopy, and ex situ grazing X-ray diffraction. Nanowires and nanoislands of Er silicide coexist on the Si substrate surface and a c(2 × 2) reconstruction is observed on the top of these nanostructures. The crystalline structure of the Er silicide nanostructure is found to be tetragonal ErSi₂. A Si-adatom model for the c(2 × 2) reconstruction is proposed. The total energy calculation based on the discrete-variational self-consistent multipolar cluster method identifies that the hollow site Si adatom model might be the most energetically favorable one.