It was recalled that this material suffered from microscopic hollow defects called micro-pipes. It was noted that large-angle convergent-beam electron diffraction, which was a well-established method for determining the total Burgers vector of a dislocation, had been applied to nanopipes in GaN. However, this method could not be successfully used here because the micro-pipes in SiC usually had diameters which were some orders of magnitude larger than those of the nanopipes in GaN. The present results showed that the micro-pipes were hollow-core dislocations, according to Frank's model, but contained dislocations of mixed type.

J.Heindl, W.Dorsch, H.P.Strunk, S.G.Müller, R.Eckstein, D.Hofmann, A.Winnacker: Physical Review Letters, 1998, 80[4], 740-1