Valence band offset of ZnO∕GaAs heterojunction measured by x-ray photoelectron spectroscopy

Abstract

X-ray photoelectron spectroscopy has been used to measure the valence band offset at the ZnO∕GaAs heterojunction interface. The valence band offset is determined to be 2.39±0.23eV. As a consequence, a type-II heterojunction with a conduction band offset of −0.44±0.23eV is found. The directly obtained value is in good agreement with the result of theoretical calculations based on the interface-induced gap states and the chemical electronegativity theory.