FRACTAL ANALYSIS OF FIELD-INDUCED EFFECTS ON THIN-FILMS OF NICKEL

Thin films of nickel deposited on mica substrates have been investigat ed using scanning tunneling microscopy (STM). The STM topograph repres ents a clear microscopically repeated structure on the nickel thin fil m surfaces. When a voltage pulse was applied normal to the film surfac e, large clusters which were present on the virgin sample fragmented i nto smaller similarly looking clusters. This surface topographic data analysis was carried out in terms of fractal dimension (D), which is a single parameter quantification (surface roughness) over many orders of magnitude. It is observed that the application of voltage pulse cha nges surface morphology quite drastically and restoration takes place in a few minutes. The present analysis in terms of fractal dimension o f the surface is in good agreement with expected changes in surface mo rphology.