Dresden 2011 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 44: Poster Session I

HL 44.26: Poster

Dienstag, 15. März 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.