6H- and 4H-silicon carbide for device applications

4H- and 6H-SiC crystals with the values of N-d-N-a from 5 10(18) cm(3) to less than 2 10(15) cm(-3) have been grown. Material with high resistivity is of great importance for high temperature electronics and other severe environments electronics based on silicon carbide as well as nitrides based electronics. Optical absorption of the samples became significant from the values of N-d-N-a, higher than.10(17) cm(-3). The samples with the values of N-d-N-a, higher than 10(18) cm(-3) are practically nontransparent in the IR region for wavelengths higher than 2 micrometers. The samples with low N-d-N-a, values are practically transparent over entire visible range and IR range up to 5 mu m. Such optically transparent crystals are of great importance for radiation-hardened, high operation temperature windows and transparent substrates for optoelectronic aevlces. Cathodoluminescence (surface mapping and spectroscopy), PL mapping, IR absorption/reflection spectroscopy, X-ray topography and optical microscopy have been employed for investigations of the 4H- and GH-SIC crystals grown by sublimation method and results of the investigations are compared.