Regensburg 2013 – scientific programme
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MI: Fachverband Mikrosonden
MI 8: Nanostructured Oxide Thermoelectrics - Joint Session with DF related to SYTS
MI 8.3: Talk
Wednesday, March 13, 2013, 13:10–13:30, H9
Indium-oxide-based Seebeck gas sensors — •Markus Mischo1, Volker Cimalla2, Oliver Ambacher1,2, and Friedemann Völklein3 — 1Laboratory for Compound Semiconductor Microsystems, Department of Microsystems Engineering - IMTEK, University of Freiburg, Germany — 2Fraunhofer Institute for Applied Solid State Physics Freiburg, Germany — 3RheinMain University, Institute of Microtechnologies
The intention of this research is to develop a highly sensitive long-lasting ozone sensor based on the thermoelectric effect. The thermoelectric, or Seebeck effect is the direct conversion of temperature differences into electricity. Direct thermoelectric gas sensors are based on the dependency of the Seebeck coefficient on the surrounding gas concentration. Beside the Seebeck coefficient there are several other important parameters which have an influence on the thermoelectric power. Generally, the thermoelectric power is characterized by the figure of merit ZT: ZT = (S2σ/κ)T where S, σ, κ and T are the major influencing parameters, namely the Seebeck coefficient, the specific electronic and thermal conductivity, respectively, and the temperature. Compounds such as InN, InAs, and InOx have good thermoelectric properties. In addition, the Fermi level and the surface band bending can be modified by specific gas adsorption, while thermal conductivity is decreased by reducing the grain size in the material. These effects are used for a highly-sensitive Seebeck gas sensor. The sensors are able to compete with conventional resistive gas sensors regarding accuracy, reproducibility and response time.