Study of photomodulated reflectance in 6H-SiC single crystals

The effect of ultraviolet irradiation of the surface of silicon-carbide (6H-SiC) single crystals on their optical reflectivity in the visible and violet spectral regions is studied. It is shown that the photoreflection-signal intensity is maximal, if the light beam is incident at the Brewster angle and polarized parallel to the plane of incidence. The relative change induced in the refractive index of the surface layers of a crystal (10$^{-3}$) upon exposure to nitrogen laser radiation, caused by the generation of nonequilibrium free charge carriers in the conduction band of the material, is established.