Co on thin Al2O3 films grown on Ni3Al(100)

The growth of Co on thin Al2O3 layers on Ni3Al(1 0 0) was investigated by Auger electron spectroscopy, high resolution electron energy loss spectroscopy (EELS), and scanning tunneling microscopy. At 300 K, Co grows in three-dimensional clusters on top of the Al2O3 layer. A defect structure of the alumina layer plays a crucial role during the early stage of Co growth. After deposition of 10 Angstrom of Co, a complete screening of the dipoles of the Al2O3 layer due to the Co film is found in the EELS measurements. Annealing the Co film reveals a process of coalescence of Co clusters and, above 700 K, diffusion of the Co atoms through the oxide film into the substrate takes place. (C) 2003 Elsevier Science B.V. All rights reserved.