Contour loop analysis of multi-affine nanostructure AZO rough surfaces

Morphology of multi-affine aluminum-doped zinc oxide (AZO) thin films during spray pyrolysis growth process is characterized by contour loop analysis. The results show that the fractal dimension of each contour loop, D-f, is different for various level cuts (in contrast to monofractal structures). Averaging it on all levels leads to a value D-f = 1.13 +/- 0.02, which remains constant during the growth process. Furthermore, there is a crossover to percolation regime with the exponent D-fp = 1.42 +/- 0.02 . Fractal dimension d of all contour loops, calculated by the box-counting method, decreases with the thickness, while the decreasing behavior is not as the monofractal structures (d = 2 - H) and is influenced by the whole values of h(q) spectrum. To find the distribution of crystalline grains in the AZO rough surfaces during the growth process, the area cumulative distribution of loops was investigated. The results indicate that the exponent, mu, decreases with enhancement of thickness during the growth process. The loops radius is linearly proportional to the grain size of deposited thin films, which could be introduced as a new numerical parameter for determining this experimental measure.