Absolute deformation potentials and band alignment of wurtzite ZnO, MgO, and CdO

Using first-principles methods we calculate the absolute deformation potentials a(v) and a(c) of wurtzite ZnO, MgO, CdO, and the band offsets at MgO/ZnO and ZnO/CdO interfaces. We find that the absolute deformation potentials of these oxides are systematically smaller in magnitude than those of the corresponding nitrides (GaN, AlN, and InN). The MgO/ZnO and ZnO/CdO heterojunctions exhibit type-I band lineups, in which the narrower band gap on the right (ZnO and CdO) is contained within the wider gap on the left (MgO and ZnO). The conduction-band offsets Delta E(c) at these junctions are much greater than the valence-band offsets Delta E(v). We explain these results in terms of the energetic position of the anion s and p valence states relative to the cation s, p, and d valence states.