THE INFLUENCE OF SURFACE-ROUGHNESS ON ELECTRONIC TRANSPORT IN THIN-FILMS

In thin films, the structure of the surfaces considerably influences the transport of conduction electrons. For mesoscopic roughnesses in the range of a few nm, this is due to the varying film thickness, which gives rise to a spatially fluctuating conductance. Moreover, microscopic roughnesses can contribute to the scattering of the electrons and therefore additionally enhance the thin-film resistivity. For a quantitative understanding of the transport in these systems, a detailed investigation of the surface roughness combined with measurements of the electronic properties are necessary. Here, we discuss STM imaging of various metal films and the application of these results to the interpretation of electronic thin-film properties. Provided reasonable resolution of STM in the nm range, a good correspondence of STM results with the electrical behaviour of growing metal films can be established. Furthermore, a detailed two-dimensional analysis allows for a calculation of the potential on current-carrying thin films. On the other hand, this method supplies reliable values for the electronic transport parameters.