ENHANCED RESPONSE TO METHANE FOR SNO2 THIN-FILMS PREPARED WITH THE CVD TECHNIQUE

SnO2 thin films were grown by means of the CVD technique, starting from dibutyltin diacetate as the precursory species. A good response of SnO2 thin films towards hydrogen, ethyl alcohol and especially methane was observed in the temperature range 300-500-degrees-C. The gas sensitivity DELTAG/G towards 1000 ppm of hydrogen, ethyl alcohol and methane at the temperature of 350-degrees-C was equal to 200, 100 and 30, respectively; on the contrary, the response to CO, NO(x) and other hydrocarbons was almost negligible. If the temperature is augmented from 350 to 500-degrees-C, an increase of the sensitivity to methane together with a lower sensitivity to hydrogen is observed. Therefore, the sensor selectivity to methane could be improved by pulsing the sensor operating temperature between 350 and 500-degrees-C.