A geometrical approach was proposed for GaN layers, which were grown onto (00•1) Al2O3, in order to explain the formation of {10•0} inversion domain boundaries. As the epitaxial relationship was due to the continuation of anion stacking along the growth direction, the Ga atoms of the first layers had a choice of sites to occupy. Therefore islands which were related either by displacement vectors, corresponding to the usual stacking fault of the hexagonal close-packed structure, or inversion domains could form naturally on the (00•1) sapphire surface. The inversion domains were found to be generated mainly at surface steps, where they were shown to minimize the large misfit (20%) along the c-axis.

Growth Defects in GaN Layers on Top of (0001) Sapphire: a Geometrical Investigation of the Misfit Effect P.Ruterana, V.Potin, B.Barbaray, G.Nouet: Philosophical Magazine A, 2000, 80[4], 937-54