Nanosecond laser nanostructuring of fused silica surfaces assisted by a chromium triangle template

Highlights: • The ns- laser irradiation of Cr triangle on SiO₂ allows the structuring of the substrate. • The resultant structures are dependent on the laser parameter. • The resultant structures were measured by AFM, SEM and EDX. • Periodic pyramidal like structures in SiO₂ can be produced applied ∼650 mJ/cm². - Abstract: The well-reproducible, fast and cost-effective nanostructuring is a big challenge for laser methods. The laser nanostructuring of fused silica assisted by chromium nanotriangles was studied using a KrF excimer laser (λ = 248 nm, Δt_p = 25 ns, top hat beam profile). Therefore, a fused silica substrate was covered with periodically ordered polystyrene (PS) spheres with a diameter of 1.59 μm. Subsequently, this system was covered with 30 nm chromium by electron beam evaporation. Afterwards the PS spheres were removed and the bare and resultant periodic Cr triangles were irradiated. The laser irradiation with high laser fluences resulted in a removal of the chromium and in localized modifications of the fused silica like a localized ablation of the fused silica. The resultant structures were studied by scanning electron (SEM) and atomic force microscopy (AFM) as well as the surface composition was analysed by energy-dispersive X-ray spectroscopy (EDX). The laser process allows the production of well-defined periodic hole structures into the fused silica surface where the resultant surface structure depends on the laser parameters. The multi-pulse irradiation of the Cr/SiO₂ sample with moderate laser fluences (Φ ∼ 650 mJ/cm²) allows the fabrication of periodic pyramidal-like structures (depth Δz = 130 nm).