Determination of the valence band offsets at HfO2/InN(0001) and InN/In0.3Ga0.7N(0001) heterojunctions using X-ray photoelectron spectroscopy

The valence band offset (VBO) at a InN/In0.3Ga0.7N(0001) as well as HfO2/InN(0001) heterojunction is investigated by X-ray photoelectron spectroscopy using monochromated AlK alpha radiation. The InN and In0.3Ga0.7N films were grown using plasma-assisted molecular beam epitaxy, whereas HfO2 layers were deposited by plasma-assisted electron beam evaporation. The VBOs were determined by analysing the core level binding energy and valence band maxima of bulk-like films as well as of In0.3Ga0.7N and InN layers covered with 5 nm thick overlayers of InN and HfO2, respectively. The resulting VBO values are similar to 0.5 eV for the InN/In0.3Ga0.7N heterojunction and similar to 0.9 eV in the case of the HfO2/InN heterointerface. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim