Room temperature operating ammonia sensor based on tellurium thin films

Tellurium thin films were studied for its use as ammonia gas sensors operable at room temperature. The films showed a reversible increase in resistance when exposed to ammonia and the response was found to be linear in the range of 0-100 ppm. The interaction of ammonia with tellurium film was investigated using Raman, XPS and impedance spectroscopy techniques. The results showed that ammonia reduces tellurium oxide on the surface and grain boundary region of the film to tellurium. This reduces majority carrier density in the film and thereby decreases the conductivity of the film. (C) 2003 Elsevier B.V. All rights reserved.