Valence-band offset of epitaxial ZnO∕MgO (111) heterojunction determined by x-ray photoelectron spectroscopy

Abstract

The valence-band offset of ZnO∕MgO (111) heterojunction has been directly measured by x-ray photoelectron spectroscopy. Excluding the strain effect, the valence-band offset is determined to be 0.87±0.20eV, and the conduction-band offset ΔEC is deduced to be −3.59±0.20eV, indicating that ZnO∕MgO heterojunction has a type-I band alignment. The conduction-band and valence-band offset of MgO∕ZnO is used to interpret the origination of p-type conduction in undoped MgxZn1−xO alloy and deeper acceptor level in undoped and N-doped p-type MgxZn1−xO alloy than in ZnO.