Mechanism Insights into Nanostructuring and Wettability on Au Thin Film: Effect of Substrate and Low-Energy Ion Irradiation

The nanostructuring of Au thin films induced by ion irradiation is significantly affected by substrate interactions, where processes such as sputtering, diffusion, and dewetting are pivotal in determining the evolution of surface morphology and wettability. The 8 keV Ne ion beam is irradiated on a 10 nm Au thin film on silicon and glass substrates. The surface morphologies of the pristine and irradiated samples are meticulously scrutinized using Atomic Force Microscopy (AFM) to understand the resultant ion irradiation induced Au nanostructures on both substrates. Contact angle measurement and Rutherford Backscattering Spectrometry (RBS) are utilized to explore the wettability of the surface and to determine Au contents on the surface, respectively. The reduction in the peak of RBS is the decrease in Au metal contents on the surface due to ion-induced nuclear sputtering. Wettability of the surface is changed with ion-induced modification in surface morphology. A 2D Detrended Fluctuation Analysis (2D-DFA) is employed to ascertain the Hurst exponent and fractal dimension to understand the wettability and nanostructuring with fractals. The formation of NSs is the result of a dynamic interaction between the processes of nuclear sputtering, dewetting, surface diffusion, and the effect of the morphology of the substrate.