Theory of the copper vacancy in cuprous oxide

Density-functional theory is used to examine aspects of the copper vacancy (V-Cu) in cuprous oxide (Cu2O). The normal vacancy configuration, obtained by simple removal of a Cu atom from the lattice, is found to be 0.1 eV higher in energy than a split vacancy configuration wherein a nearby Cu atom is displaced toward a normal vacancy site by half the bulk Cu-Cu separation. Jumps between the normal and split vacancy configurations are predicted to be rate limiting for V-Cu diffusion with an energy barrier of 0.3 eV. Binding of V-Cu to substitutional aluminum (Al-Cu) and indium (In-Cu) is examined. The neutral (Al-Cu+2V(Cu)) complex is found to have a binding energy of 3.3 eV whereas the neutral (In-Cu+2V(Cu)) complex is bound by 1.7 eV. The magnitudes of these binding energies suggest that Al-Cu and In-Cu should inhibit V-Cu diffusion in Cu2O. (C) 2002 American Institute of Physics.