Surface modulation of silicon surface by excimer laser at laser fluence below ablation threshold

Controlled single step fabrication of silicon conical surface modulations on [311] silicon surface is reported utilizing KrF excimer laser [λ=248 nm] at laser fluence below ablation threshold laser fluence. When laser fluence was increased gradually from 0 to 0.2 J/cm2 for fixed 200 numbers of shots; first nanopores are observed to form at 0.1 J/cm2, then very shallow nanocones evolve as a function of laser fluence. At 0.2 J/cm2, nanoparticles are observed to form. Up to 0.15 J/cm2 the very shallow nanocone volume is smaller but increases at a fast rate with laser fluence thereafter. It is observed that the net material volume before and after the laser irradiation remains the same, a sign of the melting and resolidification without any ablation.