Formation of Co ultrathin films on Si(111): 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(I 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 angstrom and in the Co film at d = 1-2 angstrom. 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 angstrom (c) 2007 Elsevier B. V. All rights reserved.