Growth and Characterization of Pure and Doped SnO2 Films for H2 Gas Detection

Pure and the transition metal (TM) doped SnO2 films were prepared by the sol-gel method. The surface morphology and microstructure of the grown films were characterized by a wide range of techniques. Generally, various TM doping resulted in a reduction of the particle size, as well as a smaller size of various surface features. The films were tested for the gas sensing applications. In the air containing 500 ppm H2, the optimum operating temperature for the pure SnO2 films was 250 oC, which showed a sensitivity of S=3.9 and a recovery time of 84 s. Doping of 5 at% W increased the sensitivity significantly (S=25.8) at the same operating temperature, while the recovery time was reduced to 72 s. For the 5at% Pd doped SnO2 films, the sensitivity was only slightly improved (S=4.4), however they showed the quickest recovery time of 60 s. Doping of Mn did not improve the H2 sensing sensitivity and the doped films showed a poor thermal stability at the elevated temperatures.