Self-affine fractal vapour-deposited gold surfaces characterization by scanning tunnelling microscopy

Abstract

The morphological evolution of the surfaces of gold deposits grown from the vapour on smooth glass under nonequilibrium conditions and incident angle near substrate normal is studied at the nanometer level by scanning tunnelling microscopy. For an average film thickness equal to or greater than 500 nm, the interface thickness (ξ) reaches a steady state. Under these conditions, ξ depends on the scan length (L) as ξ ∝ L^α with α = 0.35 ± 0.05 for L > d_s, where d_s is the columnar size, and α = 0.89 ± 0.05 for L < d_s. These results indicate that the growing surface spontaneously reaches a steady state and it can be described as a self-affine fractal. The value of α for L > ds agrees with the prediction of ballistic deposition models without restructuring, whereas that for L < d_s exceeds the prediction of ballistic models including restructuring.