Electrical conduction properties of SiC modified by femtosecond laser

We have observed the electrical conduction properties of silicon carbide (SiC) that was locally modified by femtosecond laser. The current-voltage (I-V) characteristics of laser-modified regions were measured. Intriguingly, when the polarization of the laser beam was parallel to the scanning direction, the resistance of the modified region decreased with increasing the irradiated fluence. The resistance of the region irradiated at a fluence of 86 J /cm² decreased by more than six orders of magnitude compared with the non-irradiated one. In contrast, when the polarization of the laser beam was perpendicular to the scanning direction, the resistance of the modified region did not show the significant reduction. From the scanning electron microscope observations and Raman spectroscopy, we suppose that the difference of the resistance for each polarization direction is due to the difference of the chemical composition generated in laser modified region. (author)