THE OPTICAL ABSORPTION BANDS AND THEIR ANISOTROPY IN THE VARIOUS MODIFICATIONS OF SiC

The optical absorption of 4H, 6H, 8H, and 15R Si C crystals has been measured in the wavelength range from 0. 35 to 2. 5 mu with polarization of light parallel and perpendicular to the c-axis of the crystals. The observed absorption bands are assumed to be due to electron excitation from the conduction band minimum to other sites of increased density of states in the higher, empty bands. In all modification a strong anisotropy of free carrier absorption is found.