Self-affine fractal electrodeposited gold surfaces

Abstract

The morphological evolution of columnar gold electrodeposits grown at 100 nm s ⁻¹ by electroreducing a gold oxide layer on a gold cathode has been studied at a nanometer level by scanning tunneling microscopy. The interface thickness (ξ) depends on the scan length (L) as ξ∝ L ^α with α=0.49±0.07 for L > d_s, where d_s is the average top columnar size, and α=0.90±0.07 for L < d_s. These results prove that the growing surface can be described as a self-affine fractal for length scales greater than the columnar size. Conversely, the columnar surface approaches the behavior of an Euclidean surface.