Fabrication of microcraters on silicon substrate by UV nanosecond photonic nanojets from microspheres

We report briefly on the fabrication of arrays of nano- and micro-craters on silicon (Si) substrates using films of C18 functionalized 1 μm silica (SiO2) particles deposited by the Langmuir-Blodgett (LB) technique. The films are illuminated with UV nanosecond laser pulses. Local substrate ablation is observed at low fluences well below the damage threshold of silicon (1 J/cm2). The result is quantitatively explained through FDTD simulations of the micro lensing effect associated with the microspheres. Change in feature size and morphology with number of shots and laser fluence is investigated. In multi-shot irradiation experiments, the produced arrays of well-defined craters rely on the combination of direct laser ablation and laser surface cleaning or annealing as evidenced by Atomic Force Microscopy (AFM) technique