SELF-AFFINE FRACTAL VAPOR-DEPOSITED GOLD SURFACES CHARACTERIZATION BY SCANNING TUNNELING MICROSCOPY

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 (xi) reaches a steady state. Under these conditions, xi depends on the scan length (L) as xi is-proportional-to L(alpha) with alpha = 0.35 +/- 0.05 for L > d(s), where d(s) is the columnar size, and alpha = 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 alpha for L > d(s) agrees with the prediction of ballistic deposition models without restructuring, whereas that for L < d(s) exceeds the prediction of ballistic models including restructuring.