Laser-induced micron and submicron ordering effects in quasi-percolated nanostructured silver thin films

Quasi-percolated nanostructured silver thin films are used as the starting morphology for inducing simultaneously changes in shape and ordering effects by laser irradiation. The complex fingered nanostructures are transformed into nanospheres which in turn are arranged in micro-circular patterns when irradiated through a pinhole. These transformations are characterized by transmission electron microscopy and atomic force microscopy. The observed effects are explained using Fresnel diffraction theory. Good agreement with the experimental results is obtained. These results suggest that precise patterning engineering can be achieved through control of the spatial parameters such as the pinhole diameter and the distance from the mask to the sample.