EFFECT OF PALLADIUM DOPING AND FILM THICKNESS ON THE H-2-GAS SENSING CHARACTERISTICS OF SNO2

Gas-sensing characteristics of undoped and Pd-doped tin oxide films ha ve been investigated. The thin films are prepared on a surface-oxidize d silicon wafer by the reactive r.f. sputtering method and tested for detection of hydrogen gas. Polycrystalline thin films consisting of fi ne grains approximate to 100 Angstrom in size show excellent sensitivi ty to H-2 gas, whereas amorphous films are insensitive. Pd-doping into tin oxide enhances the gas sensitivity and reduces the operating temp erature at which the sensitivity becomes maximized. It is found that t he gas sensitivity also depends largely on the film thickness.