Electrical properties of SnO2 and SnAcAc based gas sensors -: DC and AC measurements

In this work we have studied influence of activation process to electrical properties of tin dioxide (SnO2) and tin acetylacetonate (SnAcAc) based thin layer sensors. In the experiments sandwich sensing structures were used. They were prepared by pulsed laser deposition (PLD). The basic materials (SnO2 and SnAcAc) were doped by Pd2+ and Pd surface catalyst was deposited-by cathode sputtering. Electrical properties and responses to various atmospheres were characterized by alternating current (AC) and direct current (DC) measurements. Impedance spectroscopy was used as AC measurement and investigation of temperature dependence of resistance as DC measurement. The-impedance measurement was carried out in order to suggest the equivalent circuit of the sensor. To obtain influence of temperature and composition of atmosphere on the DC resistance we have used so called T-scan. The T-scan method means resistance measurement with progressive increasing temperature and contemporary periodical changing of atmosphere. To investigate the influence of composition of the atmosphere five gases was employed with a wide range of properties (from pure O-2 as oxidising gas to the mixture of 12% H-2 in Ar as reducing gas).