Influence of CuO on temperature dependent H2S gas sensing performance of ZrO2 thick film resistor

Abstract

Popular   screen printed   ZrO₂ thick film resistor was formulated for characterization. These films were surface modified by dipping them in 0.1 M CuCl₂ aqueous solution for the time intervals of 5,10,20, 30 and 40  minutes. Surface morphology and   elemental composition were studied using scanning electron microscopy coupled with energy dispersive   spectroscopy. It was observed that Cu converted into CuO at 200^oC during sintering of the films and this p-type oxide plays role with n- type ZrO₂ for H₂S gas sensing. X-diffraction confirmed the polycrystalline nature of pure ZrO₂ powder and influence of copper on film surface disappear the polymorphs and only strong crystalline peak was observed. It was good indication for gas sensing. Bandwidth reduction was observed   by characterizing film with UV spectroscopy techniques. Pure ZrO₂ film sample was shown wide bandwidth than sintered and modified film.  The gas sensing performances of various gases were tested previously and it is reported for Ammonia except oxygen. Negative temperature coefficient of the CuO activated film shift response to H₂S gas at elevated temperature between 300^oC to 450 ^oC.  Maximum Gas sensing response was observed at operating temperature 450^oc for 100ppm concentration. It was observed temperature, thickness and concentration dependent. Quick response time and fast recovery were recorded.

Keywords: thick film , CuO activated, H₂S gas sensor, bandwidth reduction, quick response and fast recovery