Picosecond Pulse Laser Microstructuring of Silicon

We report the experimental results of picosecond pulse laser microstructuring (pulse duration 35 ps, wavelength 1.06 μm, repetition rate 10 Hz) of silicon using the direct focusing technique. Arrays of sharp conical spikes located below the initial surface have been formed by cumulative picosecond pulsed laser irradiation of silicon in SF₆. Irradiation of silicon surface in air, N₂, or vacuum creates ripple-like patterns, but does not create the sharp conical spikes.