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Periodic fringed patterns with four periods in the range 1.8-10.2 μm have been produced in continuous Ag films that have thicknesses of 14.6 nm and 19.5 nm by exposing a phase mask to single pulses of an excimer laser operating at 193 nm. The films were patterned either as-grown or after homogeneous exposure to the same laser beam. For fluences above the threshold, the films undergo liquid-state dewetting that, from low to high fluences, leads to their break into holes, fingers or elongated features and finally to isolated nanoparticles irrespective of the period, thickness or fluence. The period determines the range of fluences to achieve the different morphologies since the temperature profile across the pattern depends on the period due to the existence of significant lateral heat flow across the pattern. The maximum temperature achieved at the intensity maxima/minima sites thus decreases/increases as the period decreases, leading to solid-state dewetting at regions around the intensity minima; the shorter the period, the higher this type of dewetting. These regions eventually overcome the melting temperature for the shortest period and intermediate fluence, leading to the complete transformation of the films. Finally, the initial film morphology (discontinuities or holes) rather than thickness plays an essential role in the level of transformation at fluences around the threshold.

Silver is widely used for a fabrication of plasmonic devices due to its unique optical constants. Nanostructured Ag layer can exhibit strong localized surface plasmon resonance, which mainly affects its optical behavior in visible and near infrared spectra. The nanostructure of the Ag layer is mainly influenced during the initial stage of the silver nucleation. Therefore we focused our attention on the study of this stage of the silver growth. The nanostructured ultra-thin silver layers were prepared by means of the magnetron sputtering. The nucleation mode and the resulting nanostructure was controlled by the deposition conditions. The initial stage of the nucleation and the layer growth was studied by means of an optical monitoring, which is based on a principle of spectrophotometric measurement of sample reflectivity. The measured data were fitted to a model of layered structure. The non-continual (Volmer-Weber) mode of the layer nucleation was clearly distinguished in the monitored data. Thus we were able to estimate the point of the non-continual layer coalescence as well as the subsequent evolution of the surface roughness. The prepared nanostructured Ag layers were analyzed by Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). Optical properties were studied by spectroscopic ellipsometry and spectrophotometry.The aim of this work was to study the formation of nanostructured Ag layer and its correlation to the optical behavior.

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