The incorporation of In2O3 into the ZnO wurtzite structure was investigated by using a combination of atomistic simulations and high-resolution electron microscopy. At low concentrations, the In ions were incorporated at Zn sites, with the creation of Zn vacancies in order to maintain charge neutrality. Defect clustering which involved two In substitutional ions that surrounded a Zn vacancy was energetically favored. At higher concentrations, In2O3 was accommodated via a series of inter-growth phases. These consisted of extended planar defects which were stacked along the c-axis of the hexagonal wurtzite structure. A model which was proposed for the In2O3-(ZnO)n phases consisted of two In2O3 layers which were oriented along the (00•1) planes of ZnO and were separated by a ZnO wurtzite layer that was n/2 unit cells thick. Each wurtzite region was displaced from the next by a translation of 1/3<01•0>. The associated solution energies of the various inter-growth phases were similar in magnitude, and were much lower than the solution energies for either isolated defects or defect clusters.

Planar Intergrowth Structures in the ZnO-In2O3 System. McCoy, M.A., Grimes, R.W., Lee, W.E.: Philosophical Magazine A, 1997, 76[6], 1187-201