Strategies to enhance the carbon monoxide sensitivity of tin oxide thin films

In this work electrical response of SnO2 thin film as a function of thickness was studied in order to determine the optimum of this parameter to detect carbon monoxide, finding out that thickness around 200nm showed the highest response. Structural characteristics of tin oxide such as grain size and net distortions were also analysed. On the other hand, a study of two catalytic metals (Pt and Pd) and their influence on sensing parameters was also carried out. Tests under controlled atmospheres and XPS analyses showed that the doping technique that provided a suitable quantity and doping profile of metal for CO detection was the so called "buried layer" when Pt was used as catalyst. Therefore, a deeper study of the latter film was performed, in order to establish some of its electrical characteristics, moisture influence on response and long-term stability. (C) 2003 Elsevier B.V. All rights reserved.