Evolution of structured silicon after picosecond laser irradiation

We prepare the black silicon by directly irradiating crystalline silicon with picosecond laser pulse in atmospheric environment. The grating scanning mode is used in the irradiation process and a regular 20 μm × 20 μm square grating are obtained on the silicon surface. The evolution of surface microstructure with the change of scanning speed and laser pulse energy is preliminarily studied. When the pulse energy is 4.78 μJ and scanning speed is 200 mm/s, picosecond laser can achieve drilling a hole on silicon surface, and the hole will become larger as the the number of pulses increases. In addition, laman spectra is measured and results show picosecond laser processing does not change the crystal phase.