EVIDENCE OF PURE DIFFUSION PROCESS DURING GROWTH OF GOLD-FILMS

The surface roughness of evaporated gold films has been studied by sca nning tunnelling microscopy and analysed by a Fourier transform method . The power spectrum S(q, t) presents a clear q(-gamma) dependence in the high-frequency region and t(beta) behaviour of the total interface width of the films. The values obtained for the two exponents, in the range of 300-18 000 Angstrom thickness studied (gamma = 4.1 +/- 0.1 a nd beta = 0.26 +/- 0.02), agree with the theoretical predictions (gamm a = 4 and beta = 0.25) for a pure diffusion-controlled process but not with a re-evaporation process. The power spectrum for high frequencie s shows good correlation for different him thicknesses, describing sca ling without anomalous behaviour. (C) 1998 Published by Elsevier Scien ce B.V. All rights reserved.