Observation of Continuous and Non-continuous Laser Induced Periodic Structures on Silicon

In this work we have demonstrated the formation of continuous and non-continuous laser-induced periodic structures on silicon substrate (SiLIPS) using nanosecond (ns) laser. The continuous SiLIPS were generated in air by linearly polarized ~2 ns laser pulses. The optimized fluence, repetition rate and scanning velocity for generation of such structures are 0.4 J/[cm.sup.2], 40 kHz and 0.5 mm/s respectively. The period of the SiLIPS (900 nm) was found to be close to the laser wavelength and the orientation was perpendicular to the polarization of the laser beam. Further, in this work we have also shown the appearance of non-continuous SiLIPS in localized region. Based on this observation, discussion is given on the mechanism of SiLIPS formation.Keywords: Nanosecond laser, laser induced black Si, Laser induced periodic structure, Mechanism of ripple formation, Large area laser structuring