Mg composition dependent band offsets of Zn(1-x)Mg(x)O/ZnO heterojunctions.

The valence band offsets (ΔEV) of Zn(1-x)Mg(x)O/ZnO heterojunctions grown by plasma-assisted molecular beam epitaxy were measured by photoelectron spectroscopy. From the directly obtained ΔEV values, the related conduction band offsets (ΔEC) were deduced. All the Zn(1-x)Mg(x)O/ZnO heterojunctions exhibit a type-I band alignment with the ΔEC/ΔEV estimated to be 1.5, 1.8, 2.0 for x = 0.10, 0.15 and 0.20, respectively. The band offsets of Zn(1-x)Mg(x)O/ZnO heterojunctions depend on Mg composition. The accurate determination of energy band alignment of Zn(1-x)Mg(x)O/ZnO is helpful for designing ZnO based optoelectronic devices.