Fourier-transform Infrared Spectroscopy ofFemtosecond Laser-modified SiC

Characterization of femtosecond laser-modified areas on silicon carbide (SiC) was carried out through Fourier transform infrared reflectance spectra. The sample scanning was carried out during femtosecond laser irradiation to make larger modified area in order to evaluate the changes of the spectra by Fourier transform infrared spectrometer. The spectra were well fitted by the analytical function which is calculated through the dielectric functions of SiC including the effect from free carriers. The obtained parameters indicated that the enhancement of damping constant of longitudinal optical phonons after laser irradiation. This enhancement is due the degradation of crystallinity of SiC. The strong correlation between the direction of modified lines and the polarization of infrared probe light was found. This correlation opens the possible application of femtosecond lasermodification in SiC for control the optical properties in infrared region.