The Wide Bandgap Materials Group of II-VI Inc., develops, manufactures and markets n+ and semi-insulating (SI) 6H SiC crystals, including vanadium-compensated and V-free. The PVT growth process is tuned to produce high-quality semi-insulating 6H SiC boules with micropipe densities below 15 cm(-2) (for 2-inch wafers) and below 70 cm(-2) (for 3-inch wafers). Room temperature resistivity for 2-inch and 3-inch SI V-doped wafers is greater than 10(11) Omega(.)cm and 10(9) Omega(.)cm, respectively. A novel synthesis process is used for the production of high-purity polycrystalline SiC source, yielding a material in which most impurities are below their GDMS detection limits. An advanced PVT process (APVT) has been developed for the growth of V-free SI 6H SiC crystals. These APVT SiC crystals contain boron below 6.2.10(15)cm(-3), nitrogen below 4.0(.)10(15)cm(-3) and demonstrate semi-insulating behavior with rho between 10(6) and 10(11) Omega(.)cm. Photoluminescence and EPR of V-free 6H SiC has been studied and EPR data have been assigned to native point defects (C vacancy, Si antisite and C-VAC-C-Si pair).