Surface characterization of Al thin film dependent on the substrate using fractal geometry

In this paper, Al films were deposited on glass and steel substrates by using thermal evaporation technique. X-ray diffraction (XRD) analysis was used for structural characterization of Al thin films. It was found that the growth process mechanism of Al film on two substrates was different. The difference in the growth mechanism and microstructures affects the surface properties. Atomic force microscope (AFM) and field emission scanning electron microscope (FESEM) have been used to describe the surface morphology and fractal properties of Al films. The fractal properties obtained by autocorrelation function (ACF), height-height correlation function (H(r)) and Minkowski function are described and compared with each other. The results of 2D AFM images show that the Al film on the steel substrate has higher surface roughness, roughness exponent, and lateral correlation length compared to the glass substrate. However, the Al film on the glass substrate has a higher spatial complexity with a fractal dimension of Df = 2.88.