The electronic states of oxygen in gallium phosphide an example of weak bonding

Abstract

A number of important electronic properties of oxygen in GaP, which cannot be accounted for by existing theories, can be explained by a simple model based on the a1 and t2 spin orbitals formed from the four neighboring gallium valence bonds. I analyze this model and show that it provides a more realistic description of the physics of such a weakly coupled system than do conventional defect theories. I show further that in this model, for which two bonding electrons have been promoted to antibonding orbitals, the spin multiplet states are stabilized by the Coulomb and exchange energies of the Ga orbitals.