Sub-100 nm nanostructuring of silicon by ultrashort laser pulses

Techniques based on laser scanning microscopes for nanoprocessing of periodic structures on silicon with ultra-short laser pulses have been developed. Ripples of 800-900 nm spacing were obtained after laser irradiation at a wavelength of 1040 nm, a repetition rate of 10 kHz and a fluence of 2 J/cm2 in air. Smaller features of 70-100nm spacing were achieved in oil at a wavelength of 800 nm, a repetition rate of 90 MHz and a fluence of 200-300 mJ/cm2 by using a high numerical focusing objective.