TiO2 thin film based gas sensors for CO-detection

Pure titanium dioxide (TiO2) thin films were deposited and investigated as gas sensors for carbon monoxide (CO) detection. TiO2 thin films were deposited by ultrasonic spray pyrolysis technique, starting from titanium(IV) oxyacetilacetonate, onto soda-lime glass substrates. Structural, morphological, and compositional properties of the TiO2 films were obtained utilizing X-ray diffractometry, energy dispersive X-ray, scanning electron microscopy, and secondary ion mass spectroscopy techniques, respectively. Films deposited above 400 A degrees C were polycrystalline, and its X-ray pattern fit well to the TiO2 anatase structure, and no other phases were detected, whereas films deposited at lower temperatures presented an amorphous structure. The sensitivity of the TiO2 films is analyzed by varying both thickness and deposition temperature. In addition, the sensor response was measured for CO concentrations from 1 to 300 ppm at different operation temperatures, 100, 200, and 300 A degrees C. The highest sensitivity ( 300) was obtained for TiO2 thin films deposited with the lowest film thickness, at a substrate temperature of 350 A degrees C. The results obtained in this work show that the TiO2 films processed by ultrasonic spray pyrolysis exhibit very promising results for detection of CO.