Ultrafast-laser-assisted chemical restructuring of silicon and germanium surfaces

This article reports a comparative study on texturing in silicon and germanium surfaces after exposure to femtosecond laser irradiation in the gaseous environments of sulfur hexafluoride (SF6) and hydrogen chloride (HCl). The surface texturing results from the combined effect of laserassisted chemical etching and laser ablation. Optimized processing conditions have produced features on the order of nanometers in size. We demonstrate for the first time that regular conical pillars can be formed in Ge and that HCl can be used to form regular conical pillars in Si.