Title: Microstructural Characterisation of Nanograin Tin Oxide Gas Sensors.
Citation: Nanostructured Materials vol. 9 p. 43-52
Publication Year: 1997
JRC N°: JRC13105
URI: http://publications.jrc.ec.europa.eu/repository/handle/JRC13105
Type: Articles in periodicals and books
Abstract: Tin oxide thin films are employed as detectors for monitoring nitrogen dioxide and carbon monoxide levels in the atmosphere. Sensor elements are fabricated by depositing nanocrystalline tin oxide on polycrystalline alumina substrates by a reactive sputtering process. Their response is dependent on the operating temperature and can be modified by the deposition of a +platinum overlayer or by implanting ions in the tin oxide. Microstructural examination of these devices have been carried out using a combination of low voltage scanning electron microscopy, conventional and high resolution transmission electron microscopy and atomic force microscopy. Performance is improved by the ultrafine grain size (~10 nm, typically) of the active layer and the surface roughness of the substrate, which result in an effective increase of the reactive area by a factor of 2-3. Internal porosity and enhanced grain boundary diffusion in the tin oxide layer may also play a significant role. Current studies are directed towards identifying the mechanisms controlling cluster formation due to the surface migration of platinum, associated with an increase in the sensitivity.
JRC Directorate:Joint Research Centre Historical Collection

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