The response of tin acetylacetonate and tin dioxide-based gas sensors to hydrogen and alcohol vapours

The aim of this work is to investigate the properties of gas sensors with active layers prepared by pulsed laser deposition (PLD) technology. The active layers were deposited on planar sensor chips with interdigital platinum electrodes, The deposition was carried out from tin dioxide and tin acetylacetonate (SnAcAc) targets by KrF excimer laser. In some cases Pd catalyst was sputtered on the surface of the active layer. The 'as-deposited' sensors were submitted to heat treatment. The chemical composition of heat treated active layers was studied by XPS method. This method revealed the oxidation state of palladium and the distribution between organic and inorganic phase during the deposition of SnAcAc. The DC responses of the sensors to a reducing atmosphere containing 1000 ppm of hydrogen, methanol, ethanol, n-propanol and n-butanol were also measured. The maximum sensitivity S (ratio of sensor resistances S=R-air/R-gas) achieved 67 for hydrogen, 21 for methanol, 50 for ethanol, 71 for n-propanol and 44 for n-butanol. The temperature of maximum sensitivity (T-max) to distinct gases, the influence of molecular weight of detected gas on T-max and the influence of molecular weight on the sensor response speed are also discussed. (C) 2000 Elsevier Science B.V. All rights reserved.