Sensor properties of Pt doped SnO2 thin films for detecting CO

Polycristalline Pt-doped SnO2 thin films have been integrated to silicon su bstrate by ultrasonic spray deposition. This deposition technique differs f rom the usual SnO2 deposition methods by using a liquid source. It allows o ne to obtain a very fine and homogeneous dispersion of Pt aggregates which act as a catalyst for the low temperature CO detection (25-100 degrees C) b y conductance change. The influence of synthesis temperature (460-560 degre es C), concentration of Pt additive (0.1-5 at.%) on gas sensitivity has bee n studied. The realisation of gas sensor includes a gas sensitive highly po rous layer (SnO2/Pt, thickness: similar to 1 mu m). The results of electric al measurements under 300 ppm of CO for thin films in a dynamic and quasist atic regime are discussed. The narrow peak of gas sensitivity in the range of low temperatures (25-100 degrees C) is obtained for about 2 at.% Pt in t he SnO2 film. (C) 1999 Elsevier Science S.A. All rights reserved.