The 3 distinct morphologies (curved, faceted, corrugated) of curved inversion domain boundaries in this nitride were investigated by means of conventional transmission electron microscopy, convergent-beam electron diffraction, high-resolution transmission electron microscopy, analytical electron microscopy, and atomistic computer simulations. The interfacial structure and chemistry of the curved and faceted defects were studied and, based upon the experimental results, a single model was proposed which was consistent with all 3 morphologies. The interface model involved a continuous N sub-lattice, with the Al sub-lattice being displaced across a [10•1] plane, with a displacement vector of 0.23<00•1>. This displacement translated the Al sub-lattice from upward-pointing to downward-pointing tetrahedral sites, or  vice versa, in the wurtzite structure. The measured value of the displacement vector was between 0.05<00•1> and 0.43<00•1>. The variation was believed to be due to local changes in chemistry. This was confirmed by atomistic calculations which indicated that the interface was most stable when both Al vacancies and O ions were present at the interface. Also, the interface energy was independent of displacement vectors ranging from 0.05<00•1> to 0.35<00•1>. The curved inversion domain boundaries formed as the result of a non-stoichiometry within the crystal. The type of morphology was thought to be controlled by local changes in chemistry, non-stoichiometry at the interface, and proximity to other planar inversion domain boundaries. The Burgers vector of a dislocation at the intersection of planar and curved inversion domain boundaries was found to be 1/3<10•0> + <00•1>, where the measured value of  was 0.157 and the calculated value was 0.164.

A.D.Westwood, R.A.Youngman, M.R.McCartney, A.N.Cormack, M.R.Notis: Journal of Materials Research, 1995, 10[5], 1287-300