Abstract
Porous thin films of SnO2 were prepared on an alumina substrate using hydrothermally synthesized SnO2 sol, to investigate the influences of film-preparation conditions on the microstructure and H2S sensing characteristics of the thin films obtained. The sensitivity and response transient to 5ppm H2S in air depended significantly on calcination temperature, operating temperature and film thickness. The 0.6μm-thick SnO2 film calcined at an optimum temperature of 700°C exhibited gas sensitivity (the ratio of electrical resistance in air to that in gas) as high as 550 together with good response transient characteristics to 5ppm H2S in air at 200°C. The crystallite size of SnO2 as well as the pore size increased uniformly with a rise in calcination temperature, growing to 17.4nm and 21nm, at 700°C, respectively. The formation of well-defined large mesopores appears to be responsible for the excellent H2S sensing characteristics.
