High-resolution IR luminescence spectra of SiC single crystals of 4H and 6H polytypes

Low-temperature infrared luminescence and high-resolution absorption spectra of undoped high-quality SiC single crystals of hexagonal modifications 4H and 6H were investigated. Narrow lines with widths less than 0.2 cm$^{-1}$ were detected, several of which were observed for the first time. It was found that some of the lines in the 4H and 6H modifications have a similar structure, however, the lines in SiC-4H are shifted to the high-energy part of the spectrum by $\sim$180 cm$^{-1}$. For the most intense quartet in the region of 1.3 $\mu$m, the energy scheme of the levels for both 4H and 6H modifications were constructed.