Scaling of black silicon processing time by high repetition rate femtosecond lasers

Surface texturing of silicon substrates is performed by femtosecond laser irradiation at high repetition rates. Various fabrication parameters are optimized, in order to achieve very high absorptance in the visible region from the micro-structured silicon wafers as compared to the unstructured ones. A 35-fold reduction of the processing time is demonstrated by increasing the laser repetition rate from 1 kHz to 200 kHz. Further scaling up to 1 MHz is proved with potential reduction of the processing time by a factor of 65. A figure of merit xi is introduced for a quantitative guidance in the choice of fabrication parameters. (C) 2013 Optical Society of America