Stereometric and fractal analysis of sputtered Ag-Cu thin films

ABSTRACT In this paper, we have successfully deposited Ag-Cu thin films. Nanoscale morphology and nanotexture were studied using atomic force microscopy (AFM) through fractal and stereometric parameters. Additional algorithms have been developed to study new fractal parameters such as surface entropy, fractal succolarity, and fractal lacunarity. The results revealed that as the deposition time increased, films exposed isotropies between ∼65 and 82 %, which were correlated to the fractal patterns, where from #3 to #5 there were greater spatial complexities. Moreover, surface roughness increased from #1 to #3, which was observed for both Sq and Sa. Similar behavior was exhibited by the other height parameters. The height distribution asymmetry decreased from #1 to #4, unlike the flattening coefficient, which exhibited a random pattern. Other stereometric parameters revealed that #3 has the most uniform and homogeneous nanotexture. This was confirmed by the fractal lacunarity because for this deposition time the lacunarity coefficient was lower. Furthermore, all films exhibited excellent topographic uniformity and percolation, showing that the deposition time does not significantly affect surface porosity. Therefore, these results revealed that the morphology and texture of thin films can be controlled by the deposition time. In addition, the evaluated parameters showed that it is possible to determine the deposition time that presents a film with better topographic conditions for technological applications.