CRYSTALLINE IMPERFECTIONS IN 4H SIC GROWN WITH A SEEDED LELY METHOD

Commercially available 4H SiC wafers have been studied concerning their crystal quality. A variety of structure sensitive techniques has been utilized to reveal specific macro-defects in the material. Microscopy examination combined with preferential chemical etching have imaged dislocation networks, micropipes, basal plane defects and cracks. Synchrotron X-ray topographs have shown defect-associated strain and lattice misorientation arising in the vicinity of some micropipes. High resolution X-ray diffractometry and Bragg angle topography were used to provide evidence of existing domains and their misorientation. The results obtained are discussed in the context of defect origin and formation mechanisms. A comparison with 6H SiC is made to derive possible similarities of defect appearance in both polytypes.