Tin dioxide thin film gas sensor

Tin dioxide (SnO2) is the singular, most important material utilised in com mercially manufactured sensors for toxic and combustible gases. In the pres ent work, tin dioxide thin film sensors with porous microstructure and thic kness of 0.22 mu m have been fabricated on commercially available glass sli des by a novel, low-cost, modified chemical deposition technique. Here we r eport, for the first time, the details of structural and deposition charact eristics of the same films as a function of experimental parameters such as the number of dippings, bath temperature and bath concentration. In additi on, the electrical properties were studied for both as deposited and pallad ium sensitised films as a function of temperature (300-500 K) in a closed q uartz tube furnace. Further, the gas sensitivity of the palladium sensitise d tin dioxide thin film sensors was evaluated in air inside the same closed quartz tube furnace as a function of the operating temperature (150-300 de grees C) for a fixed concentration (3 vol%) of hydrogen gas with nitrogen a s the carrier gas. The sensor response could be recorded at an operating te mperature of as low as 150 degrees C. Maximum sensitivity of 90% was found to occur at a low temperature of only 200 degrees C. Above this cut-off tem perature, sensitivity of the present thin film sensors was found to suffer only moderate degradation. (C) 2000 Elsevier Science Ltd and Techna S.r.l. All rights reserved.