Experimental and theoretical band alignment of Ta2O5/ZnO stack for heterostructured devices applications

Abstract

Oxide semiconductor interfaces exhibit a promising expectation in electronic devices. The band alignment at the heterointerface plays a key role in determining the carrier transport and device performances. In this study, a Ta2O5/ZnO heterojunction is fabricated by using radio-frequency magnetron sputtering and ion beam sputtering technologies on a α-sapphire substrate. The energy-band offsets are determined by using the X-ray photoelectron spectroscopy and electron affinity rule. The heterojunction between Ta2O5 and ZnO shows a Type Ⅰ band alignment accompanied with a conduction band offset of 0.33±0.03 eV and a valence band offset of −0.38±0.03 eV. In all, this work could provide an indication for their heterostructured devices fabrications, owing to its large conduction band offset and excellent electron confinement across the heterointerface of Ta2O5/ZnO.