Domain boundaries formed during epitactical growth of α-Al2O3

This paper reports on domain boundaries characterized by transmission electron microscopy in single crystal [0001] α-Al2O3 epitactically regrown after being amorphized by stoichiometric ion implantation. The domains are facetted on (1120) and have dislocation-like features at facet intersections. End-of-range dislocation loops on (0001) appear to be the nucleation site for the domains. Diffraction contrast, high resolution imaging and convergent beam electron diffraction techniques showed that two types of domains are present which involve cation stacking sequences which are out of phase with the matrix as a result of translation along and/or inversion of [0001]. The non-inverted regions can be described as anti-phase domains, whereas those with [0001] inverted also have a basal twin character