Extended statistical analysis of rough growth fronts in gold films prepared by thermal evaporation

The surface roughness of evaporated gold films has been studied by scanning tunneling microscopy and a frequency analysis method that uses the whole i mage. The power spectrum S(q,t) presents a clear q(-gamma) dependence in th e region of high frequencies and the interface width of the films follows a t(beta) behavior. The values obtained for the two exponents (gamma = 4.1 a nd beta = 0.26) agree with the theoretical predictions (gamma = 4 and beta = 0.25) for a process controlled by pure surface diffusion in the thickness range studied. The power spectrum at high frequencies is similar for diffe rent film thickness describing a phenomenon free from anomalous scaling. We also conclude that dimensional analysis of profiles presents some practica l problems in its application. On the other hand, frequency analysis of the whole image allows us to obtain a reliable determination of surface roughn ess. [S0163-1829(99)00528-7].