Structural and dynamical properties of Al clusters adsorbed on Ni surface

The impact-induced deposition of All:, clusters with icosahedral structure on Ni(0 0 1) surface was studied by molecular dynamics (MD) simulation usin g Finnis-Sinclair potentials. The incident kinetic energy (E-m) ranged from 0.01 to 30 eV per atom. The structural and dynamical properties of Al clus ters on Ni surfaces were found to be strongly dependent on the impact energ y. At much lower energy, the Al cluster deposited on the surface as a bulk molecule. However. the original icosahedral structure was transformed to th e fee-like one due to the interaction and the structure mismatch between th e Al cluster and Ni surface. With increasing the impinging energy, the clus ter was deformed severely when it contacted the substrate, and then broken up due to dense collision cascade. The cluster atoms spread on the surface at last. When the impact energy was higher than 1 1 eV, the defects, such a s Al substitutions and Ni ejections, were observed. The simulation indicate d that there exists an optimum energy range, which is suitable for Al epita xial growth in layer by layer. In addition, at higher impinging energy, the atomic exchange between Al and Ni atoms will be favourable to surface allo ying. (C) 2001 Elsevier Science B.V. All rights reserved.