Valence-band offset of p-NiO/n-ZnO heterojunction measured by X-ray photoelectron spectroscopy

► We measured the ΔEV of NiO/ZnO heterojunction which use NiO as the epitaxial layer. ► The NiO/ZnO heterojunction has a type-II band alignment with ΔEV of 1.47 eV. ► The ΔEV of NiO/ZnO at different growth sequence of ZnO and NiO layers are different.