GAS-SENSING PROPERTIES OF CHEMICALLY DEPOSITED SNOX FILMS DOPED WITH PT AND SB

The influence of Pt and Sb additives on the gas sensitivity of chemically deposited SnO(x) films has been investigated. The temperature dependence of the resistance change and response time of SnO(x) to various gases in the air has been measured. Particular attention is paid to the CO and H-2 sensitivities at an operating temperature t less-than-or-equal-to 100-degrees-C. The non-doped and Sb-doped SnO(x) films show a low gas sensitivity at t almost-equal-to 100-degrees-C. The resistance change and response time tau of Pt-doped films depend on the annealing temperature. The SnO2:Pt Samples annealed at low temperature (t(a) less-than-or-equal-to 400-degrees-C) are gas sensitive but slow (tau = 50-500 s) at 100-degrees-C. Annealing at t(a) greater-than-or-equal-to 700-degrees-C leads to a considerable reduction of the gas sensitivity of Pt-doped films. The SnO(x) samples doped simultaneously with Pt and Sb show a high sensitivity to CO or H-2 and a fast response and recovery at t less-than-or-equal-to 100-degrees-C (tau less-than-or-equal-to 2 s). These samples prove to be sensitive to ethanol, acetaldehyde and acetic acid, but not to O2, CO2, SO2 and NO(x).