Dresden 2011 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 44: Poster Session I
HL 44.26: Poster
Tuesday, March 15, 2011, 18:00–21:00, P3
Determination of the valence band offset at selected oxide/InN interfaces — Georg Eichapfel1, •Marcel Himmerlich1, Anja Eisenhardt1, Stefan Krischok1, Andreas Knübel2, Thorsten Passow2, Chunyu Wang2, Fouad Benkhelifa2, and Rolf Aidam2 — 1Institut für Physik and Institut für Mikro- und Nanotechnologien, TU Ilmenau, PF 100565, 98684 Ilmenau, Germany — 2Fraunhofer-Institut für Angewandte Festkörperphysik, Tullastraße 72, 79108 Freiburg, Germany
The valence band offsets (VBO) at different oxide/InN(0001) interfaces are investigated for TiO2, HfO2, Al2O3 and In2O3 using X-ray photoelectron spectroscopy. These oxide materials might be potential candidates for the use as barrier material in InN based transistors. The precise knowledge of the band alignment at the oxide/InN interface is relevant to understand the carrier transport characteristics in electronic devices. InN films with a thickness of 1 µm were grown by PAMBE on GaN(0001)/Al2O3 templates. Thin oxide films were grown on top of these InN layers, within a series of varying thickness (1-5 nm). TiO2 and HfO2 were deposited by plasma-assisted e-beam evaporation, while for Al2O3 a remote plasma ALD process was used and In2O3 was grown by MOCVD. Thickness dependent changes of the barrier could only be found for TiO2 which exhibited the strongest degree of process-induced InN interface oxidation. The VBO values, which were determined by linear extrapolation of the thickness dependence, are 1.8 eV, 1.2 eV, 2.65 eV and 1.5 eV for the TiO2/InN, HfO2/InN, Al2O3/InN and In2O3/InN heterointerface, respectively.