Formation of Co ultrathin films on Si(1 1 1): Growth mechanisms, electronic structure and transport

The AES, EELS, AFM and resistance measurement investigations have been performed to determine the growth mechanism, electronic structure and resistance-thickness dependence of Co layers on silicon at the thickness range from submonolayer up to several monolayer coverage. These layers were obtained under UHV high-rate deposition with using re-evaporation of Co from a Ta foil. The layer-by-layer growth of Co on Si(1 1 1) with some light segregation of Si has been found on the AES data. An enlarged and reduced concentration of valence electrons in the interface Si layer at the thickness ranges 0–1 A ° and in the Co film at d = 1–2 A ° has been observed. Resistance measurement of the Co film showed a fast decrease of the resistance down to some value limited by quantum-size effect in accordance with the formation of a two-dimensional Co phase at d = 1–2 A ° .