Defect reduction in SiC crystals grown by the modified Lely method

4H-SiC crystals, 30-40 mm in diameter, have been grown by the Modified Lely method. It was already shown that 4H-SiC growth is more stable at low temperature, in the temperature range 2000-2050degreesC. The annealing of the powder in argon before the growth process at temperature higher than the growth one is proposed in this study to eliminate the surface contamination during the first step of the growth process and to improve the quality of the grown crystals. The occurrence of defects which were responsible for crack formation and polytype shift were found at the periphery of the crystal without purifying the powder. It is shown that these defects are created at the beginning of the growth process.