Mg composition dependent band offsets of Zn1-xMgxO/ZnO heterojunctions

The valence band offsets (Delta E-V) of Zn1-xMgxO/ZnO heterojunctions grown by plasma-assisted molecular beam epitaxy were measured by photoelectron spectroscopy. From the directly obtained Delta E-V values, the related conduction band offsets (Delta E-C) were deduced. All the Zn1-xMgxO/ZnO heterojunctions exhibit a type-I band alignment with the Delta E-C/Delta E-V estimated to be 1.5, 1.8, 2.0 for x = 0.10, 0.15 and 0.20, respectively. The band offsets of Zn1-xMgxO/ZnO heterojunctions depend on Mg composition. The accurate determination of energy band alignment of Zn1-xMgxO/ZnO is helpful for designing ZnO based optoelectronic devices.