Valence band offsets at oxide/InN interfaces determined by X-ray photoelectron spectroscopy
Abstract
The valence band offset (VBO) at the interface between indium nitride (InN) and selected oxide materials (Al2O3, TiO2, In2O3 and HfO2) is determined using X-ray photoelectron spectroscopy (XPS). For exact VBO determination, InN samples with oxide cap layers of varying thickness are investigated. The VBO values are extrapolated by linear regression of the thickness dependent energetic distances ΔE between the valence band maxima (VBM) at the oxide and InN surface and their corresponding heterointerface. The determined VBO values are (2.7 ± 0.2) eV for Al2O3/InN, (1.8 ± 0.2) eV for TiO2/InN, (1.5 ± 0.2) eV for In2O3/InN, (1.3 ± 0.2) eV for e-beam evaporated HfO2 on InN, and (2.0 ± 0.2) eV for atomic layer deposited HfO2 on InN. In some cases the oxide deposition process leads to an oxidation of the InN film at the oxide/InN interface (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
