It was recalled that a proposed model, for planar inversion domain boundaries in this nitride, involved a basal plane of Al atoms which were octahedrally coordinated with respect to O; with a translation of 1/3<10•1> +1/3<00•1> or 1/3<10•1>. This thin sandwich was inserted into the basal plane of the wurtzite structure. This model did not take account of interfacial relaxation phenomena, and was probably electrically unstable. Therefore, a refinement of the model was presented here. It involved the incorporation of structural relaxations that arose from modifications of the local chemistry. The interfacial structure was 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 new planar inversion domain boundary model was based closely upon the original model. However, the local chemistry was changed so that every fourth O atom was replaced by a N atom. Atomistic computer simulation of these defects, using a classical Born model for ionic solids, confirmed that the stability of these defects arose from an adjustment of the local chemistry. The resultant structural relaxations took the form of an 0.3mrad twist parallel to the interface, a contraction of the basal planes adjacent to the planar inversion domain boundary, and an expansion of the c-axis component of the displacement vector. The new displacement vector across the interface was: 1.3<10•1> + <00•1>, where the measured value of  was 0.387, and the calculated value was 0.394.

A.D.Westwood, R.A.Youngman, M.R.McCartney, A.N.Cormack, M.R.Notis: Journal of Materials Research, 1995, 10[5], 1270-86