Berlin 2018 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 13: Oxide Semiconductors for Novel Devices (Focussed Session): Session III

DS 13.3: Hauptvortrag

Dienstag, 13. März 2018, 10:30–11:00, E 020

Indium Oxide and its surface electrons – a model system to study gas interaction and metal/semiconductor junctions — •Marcel Himmerlich, Theresa Berthold, Jonas Michel, Simeon Katzer, and Stefan Krischok — Institut für Physik & IMN Macro Nano, Technische Universität Ilmenau, Germany

The electron accumulation at Indium Oxide surfaces is beneficial for electronic devices that rely on adsorption processes such as gas sensors. However, it is a drawback for electron transport devices since it hinders the fabrication of rectifying metal contacts. In both cases, the manipulation of the electron density by surface reactions is one approach to optimize performance. We analyze the underlying mechanisms of adsorption processes and the formation of metal/semiconductor contacts using model in-situ experiments. For the interaction with O₂, O₃, H₂O, CO and NO_x, a clear correlation exists between adsorbate-semiconductor charge transfer, density of surface charge carriers, and the conductivity of the material. If In₂O₃ is treated by a reactive oxygen plasma, the surface electron layer is fully depleted generating a barrier for interface transport. Photoelectron spectroscopy measurements reveal that adsorption of Pt on these modified surfaces results in sufficient Schottky barriers for rectifying contacts, but fabricated devices fail. It will be demonstrated that the oxygen-rich Pt/In₂O₃ interface is critical in stability and that oxidation of Pt-based contacts is beneficial to enhance electronic barriers and to exploit the effect of electron depletion via oxygen plasma modification. Combining both processes enables performance improvement of In₂O₃ Schottky diodes.