LAUSR

Abstract Energy band lineup at hetero-interface and its physical origin have been always a fascinating issue, and are being intensely investigated. The understanding of the influence of an interlayer on the band lineup of hetero-interface provides a view of studying the band lineup of hetero-interface. Thus in this paper, the Al2O3/GeOx/Ge structure is employed, and the effect of interlayer GeOx thickness on band lineup of Al2O3/GeOx/Ge structure is studied by X-ray photoelectron spectroscopy technique. The valence band offset of Al2O3/Ge hetero-interface is found to be nearly identical (3.5 eV) for different GeOx thicknesses (0.2 nm ~ 1.2 nm). The gap states model is employed to successfully explain these results. The interfacial dipole in Al2O3/GeOx/Ge structure is nearly unchanged with GeOx thickness based on the gap states model. This indicates that the band lineup of Al2O3/GeOx/Ge structure is independent on GeOx thickness. Thus these further verify that the gap state model is feasible in elucidating energy band lineup at hetero-interfaces.