Alignment of nanoparticles formed on the surface of 6H-SiC crystals irradiated by two collinear femtosecond laser beams

Abstract

Nanoripples with periods of 150 and 80nm are formed on the surface of 6H-SiC crystals irradiated by the p-polarized 800nm and the s-polarized 400nm femtosecond lasers, respectively. When both of the two collinear laser beams focus simultaneously on the sample surface, nanoparticles are formed on the whole ablation area, and they array in parallel lines. We propose and confirm that the second harmonics in the sample surface excited by the incident lasers plays an important role in the formation of nanostructures.