Contact epitaxy by deposition of Cu, Ag, Au, Pt, and Ni nanoclusters on (100) surfaces: Size limits and mechanisms

Abstract

Low-energy deposition of individual metal clusters (6--2000 atoms) on a (100) surface is studied for copper, nickel, platinum, silver, and gold by means of molecular-dynamics simulations. For different temperatures ranging from $0\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}750\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ we determine the maximum size of clusters that will achieve complete contact epitaxy upon deposition. The results show that two mechanisms contribute to epitaxial alignment. For the smallest cluster sizes, the heat of adsorption released at the interface will immediately (ps time scales) allow the cluster to melt and become epitaxial by resolidification. This effect gives roughly the same limit for all elements studied. On longer (ns) time scales, the clusters can align epitaxially by thermally actived motion of twinning dislocations. This mechanism leads to much higher limits of epitaxy than the resolidification process. Moreover, the resulting limits differ significantly between the elements.