New Lines in High Resolution IR Luminescence Spectra of SiC Single Crystals of the 4H and 6H Polytypes

We have studied high-resolution low-temperature IR luminescence and absorption spectra of undoped high-quality SiC single crystals of the 4H and 6H hexagonal modifications. Narrow lines with a width of smaller than 0.2 cm–1 have been revealed, with some of which being observed for the first time. We have found that some of the lines in the 4H and 6H modifications have similar structures; however, the lines in SiC-4H are shifted to the high-energy part of the spectrum by ~180 cm–1. For the most intense quartet in the range of 1.3 µm, we have succeeded in constructing the energy structure of levels for both the 4H modification and the 6H modification based on their luminescence and absorption spectra.