Nanosecond laser-induced controllable periodical surface structures on silicon

In this paper, an effective method is proposed to generate specific periodical surface structures. A 532 nm linearly polarized laser is used to irradiate the silicon with pulse duration of 10 ns and repetition frequency of 10 Hz. Laser-induced periodic surface structures (LIPSSs) are observed when the fluence is 121 mJ/cm2 and the number of pulses is 1000. The threshold of fluence for generating LIPSS gradually increases with the decrease of the number of pulses. In addition, the laser incident angle has a notable effect on the period of LIPSS, which varies from 430 nm to 1578 nm, as the incident angle ranges from 10° to 60° correspondingly. Besides, the reflectivity is reduced significantly on silicon with LIPSS.