Nanostructural investigations on ripples prepared by femtosecond laser treatment of silicon

Abstract

Femtosecond laser irradiation of silicon surfaces results in the formation of superficial ripples if fluences close to the ablation threshold are applied. Those ripples consist of highly correlated parallel trenches with peak-to-peak widths of adjacent trenches proportional on the wavelength of the laser used. We have used a micro-machining workstation (3D-Micromac MicroPulse fs-150-10) featuring a Ti:Sapphire femtosecond laser (Clark-MXR CPA-2010) to generate ripples parallel to (110) planes on [100] silicon wafers by the application of 775 nm laser radiation. After imaging the surface by atomic-force microscopy and scanning electron microscopy, the nanostructure obtained was analysed by cross-sectional high-resolution transmission electron microscopy and initial stages of ripples were identified as pile-ups of amorphous silicon.Femtosecond laser irradiation of silicon surfaces results in the formation of superficial ripples if fluences close to the ablation threshold are applied. Those ripples consist of highly correlated parallel trenches with peak-to-peak widths of adjacent trenches proportional on the wavelength of the laser used. We have used a micro-machining workstation (3D-Micromac MicroPulse fs-150-10) featuring a Ti:Sapphire femtosecond laser (Clark-MXR CPA-2010) to generate ripples parallel to (110) planes on [100] silicon wafers by the application of 775 nm laser radiation. After imaging the surface by atomic-force microscopy and scanning electron microscopy, the nanostructure obtained was analysed by cross-sectional high-resolution transmission electron microscopy and initial stages of ripples were identified as pile-ups of amorphous silicon.