Influence of Mg content on the band alignment at CdS∕(Zn,Mg)O interfaces

In this investigation, we studied electronic properties of the CdS∕Zn1−xMgxO (x=0,0.15) interface using photoelectron spectroscopy. ZnO and (Zn,Mg)O films were deposited by magnetron sputtering from ceramic targets on thermally evaporated CdS. Valence-band offsets of ΔEV=1.2±0.1eV are determined for both interfaces. The gap difference of 0.3eV between ZnO and Zn0.85Mg0.15O is therefore fully accommodated by a different conduction-band energy, which should be well suited for modulation doping in ZnO∕(Zn,Mg)O heterostructures.