Fractal geometry and morphological assessment of Metal-Dielectric nanocomposite films

This work investigates the morphology and fractal characteristics of silver and gold films obtained by thermal evaporation at pre-percolation thicknesses. They contain both metallic and insulating (void) phases, making them metal-dielectric composites. The fractal dimensions were evaluated using two approaches: the box-counting method (Hausdorff dimension) and correlation function analysis (correlation dimension). The dependence of the fractal parameters on the films’ mass thickness was established. It was shown that values of correlation dimension are smaller than the Hausdorff dimension for both Ag and Au films, consistent with the theoretical framework of multifractal analysis. The results confirm the multifractal nature of ultrathin metallic films and highlight the significant influence of morphology on their optical and plasmonic properties. The results confirm the multifractal nature of ultrathin metallic films and highlight the significant influence of morphology on their plasmonic properties.