Regensburg 2016 – scientific programme
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DS: Fachverband Dünne Schichten
DS 40: Focussed Session: Oxide Semiconductors for Device and Energy Applications I
(Joint session of DS and HL, organized by DS)
DS 40.6: Talk
Thursday, March 10, 2016, 12:15–12:30, H11
Electrical conductivity and gas-response of the In2O3 surface electron accumulation layer — •Julius Rombach1, Oliver Bierwagen1, Alexandra Papadogianni1, Markus Mischo2, Volker Cimalla2, Oliver Ambacher3, Theresa Berthold4, Marcel Himmerlich4, and Stefan Krischok4 — 1Paul-Drude-Institut für Festkörperelektronik, Berlin — 2Fraunhofer Institut für Angewandte Festkörperphysik, Freiburg — 3Institut für Mikrosystemtechnik, Freiburg — 4Institut für Mikro- und Nanotechnologien, Technische Universität Ilmenau, Germany
Indium oxide is a well-known material for conductometric gas sensors, showing a decrease in conductance when exposed to oxidizing gases. In contrast to typically used polycrystalline films, we study MBE-grown single-crystalline In2O3 thin films as a model system with reduced complexity. Electrical conductivity of these films essentially consists of two parallel contributions: the bulk of the film and the surface electron accumulation layer (SEAL) of unknown conductance. Both these contributions are varied to understand their effect on the sensor response. Conductivity changes induced by UV illumination in air, forcing desorption of oxygen adatoms on the surface, and gas-response measurements in ozone atmosphere give a measure of the sensor response and show that the sensor effect is only due to the SEAL conductivity. Therefore, a strong sensitivity increase is achieved by reducing the bulk (or intra-grain) conductivity. Hall and Seebeck measurements will give further details helping to estimate the SEAL electron concentration and mobility.