Density-functional theory was used to examine aspects of the Cu vacancy (VCu) in the oxide. The normal vacancy configuration, obtained by simple removal of a Cu atom from the lattice, was found to be 0.1eV higher in energy than that of a split vacancy configuration in which a nearby Cu atom was displaced towards a normal vacancy site by half the bulk Cu–Cu separation. Jumps between the normal and split vacancy configurations were predicted to be rate-limiting for VCu diffusion with an energy barrier of 0.3eV. Binding of VCu to substitutional Al (AlCu) and In (InCu) was examined. The neutral (AlCu + 2VCu) complex was found to have a binding energy of 3.3eV whereas the neutral (InCu + 2VCu) complex was bound by 1.7eV. The magnitudes of these binding energies suggested that AlCu and InCu should inhibit VCu diffusion in Cu2O.

Theory of the Copper Vacancy in Cuprous Oxide. A.F.Wright, J.S.Nelson: Journal of Applied Physics, 2002, 92[10], 5849-51