Insight Mechanisms of Surface Structuring and Wettability of Ion-Treated Ag Thin Films

Insight mechanisms involved in the evolution of surface morphology and wettability of 100 MeV Ag-ion-treated Ag thin films have been studied using thermal spike and fractal analysis. The results of nanostructuring and wettability are correlated on the basis of atomic force microscopy (AFM), scanning electron microscopy (SEM), and contact angle (CA) measurements. The SEM images show ion-induced evolution of Ag nanostructures and reduction in the surface coverage area of Ag. The AFM images reveal the formation of nanostructures. The autocorrelation and power spectral density (PSD) functions are used to characterize the surface profile, and these confirm the formation of nanostructures. Fractal analysis is performed on pristine and ion beam tailored surfaces to explore the mechanism involved in nanostructuring. It is observed that interface width, lateral correlation length, and roughness exponent depend on ion doses. The variation in the wettability of surfaces is well correlated with interface width and compositional variation. Thermal spike simulations have been performed to understand the development of the surface morphology after ion treatment. The formation of nanostructures and reduction in surface coverage area are consequences of competition among the mechanisms of sputtering, dewetting, and diffusion processes.