+Although significant advances have been achieved in the field of SiC bulk crystal growth, a variety of problems remain.
+The high temperatures required in PVT growth processes limit the range of materials used in the hot zones of the reactors, for which mainly graphite is used.
+The porous material constitutes a severe source of contamination ...
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+These defects include growth spirals (stepped screw dislocations), subgrain boundaries as well as micropipes (micron sized voids extending along the c axis of the crystal) in the hexagonal polytypes.