Effects of elastic energy on the spinodal decomposition in InAlGaN materials

The purpose of our study is to determine the influence of elastic energy on the spinodal decomposition ranges of InAlGaN alloys lattice-matched to GaN. The distinction in lattice constants of the binary compounds constituting these alloys gives rise to their deformation energies. Such energies provide the tendency to disintegration that can lead to an appearance of the thermodynamically unstable states with respect to the decomposition. The initial stage of spinodal decomposition of the InAlGaN quaternary alloys is accompanied by transfers of atoms over distances of a lattice parameter. Accordingly, these transfers produce a thin two-layer region with negligibly small differences in their compositions. Formation of these layers causes the elastic energy. The alloys are represented as quaternary regular solutions. The internal deformation energy is calculated with the interaction parameters estimated by the valence force field model. The spinodal decomposition ranges of these materials are demonstrated up to 580 degrees C. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim