Topographic study of dislocation structure in hexagonal SiC single crystals with low dislocation density

We have investigated hexagonal silicon carbide with low dislocation density to reveal inherent dislocation types and structures using the bulk-sensitive synchrotron X-ray topography. This topographic study reveals that: (1) Basal-plane dislocations with the Burgers vector of 13〈1 1 2¯ 0〉 preferred to be screw dislocations along 〈1 1 2¯ 0〉 in straight shape. (2) Threading dislocations containing the Burgers vector component of 〈0 0 0 1〉 are mostly mixed dislocations containing that of 13〈1 1 2¯ 0〉. (3) Threading edge dislocations with the Burgers vector of 13〈1 1 2¯ 0〉 are of short lengths, about 30–100 μm. (4) All these dislocations are connected to convert, combine and dissociate to each other. We discuss the dislocation types and structures in terms of both the Peierls energy and elastic interaction. Moreover, we propose that the source of dislocations with the Burgers vector of 13〈1 1 2¯ 0〉 is due to the propagation from a seed crystal rather than due to the Frank–Read mechanism.