Silicon micro-structuring using ultra-short laser pulses

Microstructures develop spontaneously on silicon surface under the cumulative short laser pulses irradiation in different ambient atmospheres. The experimental results suggest that the ambient atmospheres and the laser pulse duration play key roles on the microstructures formation. Only in SF6 ambient, the sharp conical spikes develop. Under the picosecond laser irradiation, silicon surface is melted before the spike arrays formed, while under the femtosecond laser irradiation, the formation of spike array does not pass through the liquid phase. The optical absorption increases remarkably from ultraviolet (similar to 0.25 mu m) to the infrared (similar to 19 mu m) for the microstructured silicon material, which promises for new device applications, such as solar cells, infrared photo-detector.