NANOPARTICULATE STRUCTURING OF SURFACES USING FEMTOSECOND LASER IRRADIATION

摘要

Nanoparticulate surfaces are generated on 3C-SiC thin films (deposited on silicon) by irradiation with an 800-nm wavelength, 120-fs pulsed Ti:sapphire laser. The ultrafast laser at low energy fluence dissociated the CVD-deposited 2-μm thin 3C-SiC film into closely packed nanoparticles within about 200-nm depth. The particles were spherical in shape with a mean diameter of 120-nm. There is no evidence of typical collateral thermal damages like ripples, columns, recast layers, and cracks. The formation of nanoparticles on the surfaces is quite an intriguing phenomenon, suggesting a plausible non-thermal mechanism that involves two steps: a defect-activated process in which the near IR wavelength light is absorbed by the defect sites of SiC films followed by a Coulomb explosion process where the intense laser field strips the electrons and permits the ions feel the Coulomb repulsion field and explode, leaving nanocraters.