It was recalled that domain structures were widespread in as-grown chemical vapor-deposited -phase crystals. Transmission electron microscopy was used here to determine the nature of the domains and domain boundaries. Selected-area electron diffraction patterns, taken from each side of the domain walls, were found to be essentially the same; but differing convergent-beam electron diffraction patterns and image contrasts were sometimes observed. It was concluded that the features were not simple stacking faults or antiphase domain boundaries or inversion boundaries. Instead, analysis showed that they were 60 rotation domains which could occur because the structure had 3-fold rotational symmetry instead of 6-fold symmetry along the c-axis of the trigonal unit cell. The domain boundaries often lay on low-index planes, but could be curved and could occur on any plane. They sometimes produced a stacking fault-like contrast.

D.S.Zhou, T.E.Mitchell: Philosophical Magazine A, 1995, 72[5], 1131-40