Large scale microstructuring on silicon surface in air and liquid by femtosecond laser pulses

► Large-scale microstructures were formed on the surface of silicon with dimensions of 1 mm × 1 mm by femtosecond laser line-by-line scanning irradiation, in air and liquid assisted. ► Scanning electron microscopy investigations exhibited homogeneous surface microstructures, such as, ripples with sub-wavelengths dimensions, Si pillars and directional arranged bacilliform structures. ► The dependence of the surface morphology on laser energy and scanning speed was analyzed.