The cluster formation of silver adatoms on carbon nanotubes was investigated to deduce the curvature effect on surface diffusion. By analyzing the cluster density as a function of the deposition time t for different diameters, d, of carbon nanotubes, the scaling form for describing the curvature effect on surface diffusion was obtained to first-order approximation. It was found that the curvature effect on the surface diffusion could well be described by using the relation between the deposition time t and the scaled deposition time τ in the form of τ∼td-z, with z being the exponent characterizing geometric properties of carbon nanotubes and the nanotube helicity. The value of z for the armchair-type carbon nanotube was larger than those for the zig-zag type and the chiral-type carbon nanotubes. The scaling form was further demonstrated and verified by numerical simulations, and was explained by the two-dimensional random walk model.

Curvature Effect on the Surface Diffusion of Silver Adatoms on Carbon Nanotubes: Deposition Experiments and Numerical Simulations. Wu, M.C., Li, C.L., Hu, C.K., Chang, Y.C., Liaw, Y.H., Huang, L.W., Chang, C.S., Tsong, T.T., Hsu, T.: Physical Review B, 2006, 74[12], 125424