Surface microtexture and wettability analysis of quasi two-dimensional (Ti, Al)N thin films using fractal geometry

Abstract

In this work, image and fractal analysis of Aluminium doped Titanium Nitride (Ti, Al)N thin films deposited by direct current (DC)/radio frequency (RF) magnetron sputtering is reported. Atomic force microscopy (AFM) data were studied to understand the impact of the Al doping concentration on the quasi two-dimensional surface morphology as well as surface texture parameters, evaluated by fractal and advanced fractal analysis. Conventional analysis shows a decrease in roughness of film surfaces along with peaks, valleys, and high surface uniformity. Furrows and contour lines generated from the topographical profile and grains were analyzed to gain a deep insight into the microtexture of the film surfaces. Power spectrum density approaches confirmed the self-affine behavior of the films with a semi-regular behavior of fractal dimension. The surface entropy did not show any significant difference indicating a globally uniform surface. Succolarity study showed a different behavior from that of furrow analysis. The effect on wettability of TiN films due to Al doping is studied based on the modified Wenzel equation and curvature pressure for fractal surfaces The hydrophobic behavior of (Ti, Al)N thin films exhibits a dependence on the fractal dimension, Hurst coefficient and fractal succolarity of the film surfaces. This study offers a deep understanding about the applicability of (Ti, Al)N thin films.