Crystalline micro/nanostructures fabrication on silicon using femtosecond laser

Abstract

The laser induced micro/ nano-meter size surface structures are fabricated by multi linear polarized femtosecond laser pulses (pulse duration τ=35 fs, wavelength λ=800 nm) irradiation at room temperature(25 ℃ ) and 400 ℃. The structures fabricated at these two temperatures show distinct temperature dependence. The grooves, which are parallel to the polarization of the laser light, can be clearly observed at almost all the structured area formed at 400 ℃ while laser induced period structures(ripples) are the most pronounced surface structure in the crater formed at room temperature. The crystallinity of these surface structures are investigated by using Raman spectroscopy. The Raman spectrum shows that all the structured area formed at 400 ℃ is crystalline(or poly-crystalline) while amorphous silicon can be observed within the structures formed at room temperature (25 ℃). These results indicate that temperature is an important parameter to be tuned to tailor the micro/nano-structure fabrication.