A study of dual conductance response to carbon monoxide of CdS and α-SnWO4 thin films
- 1 January 1994
- journal article
- Published by IOP Publishing in Physica Scripta
- Vol. T54 (T54) , 248-251
- https://doi.org/10.1088/0031-8949/1994/t54/061
Abstract
An unusual dual conductance response was found in the case of exposure of n-type semiconductors CdS and α-SnWO4 in the form of thin films to carbon monoxide. Usually, CO behaves as a reducing gas increasing the conductance of n-type semiconductors. However, at temperatures below a border temperature T*, CO did behave as an oxidizing gas decreasing the conductance of CdS and αSnWO4 thin films. T* for this dual conductance response to CO was found to be below 50 °C for CdS films. The enrichment of the surface with cadmium species had a decreasing effect on T* which was also decreasing with decreasing partial pressure of CO. For α-SnWO4 films, T* was near 250 °C depending on the partial pressure of CO. It was found that the dual response behaviour depends on temperature, CO concentration in air and tin content in the film.Keywords
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