Tunable nanostructuring of glass substrates using cost-effective nanopatterning techniques

This work investigates the creation of nanostructured glass surfaces through the solid-state thermal dewetting of gold (Au) thin films, followed by the removal of the resulting Au nanoisland (AuNI) to form craters on the glass substrate. By varying the nominal thickness of the Au film and the annealing time, we controlled the size, density, and distribution of the AuNI, which in turn affected the dimensions of the resulting craters. Characterization of these nanostructured surfaces was performed using SEM and AFM analyses, revealing significant variations in the lateral and vertical characteristics. Experimental reflectivity measurements showed up to a 20% reduction, demonstrating the tunability of the nanostructured surfaces. The Maxwell-Garnett model (MGM) was employed to theoretically model the optical properties of these surfaces, treating the craters as air-filled cylinders. The MGM parameters, including the thickness of the nanostructured layer and the filling fraction of the cylinders, were derived to match experimental data. Further theoretical optimization indicated that achieving craters with a depth of approximately 100nm could further reduce reflectivity. This tunability in nanostructuring enables the design of glass surfaces with specific optical properties, making the findings promising for applications such as solar cells, where minimizing Fresnel losses is crucial.