Effects of Pt/Pd co-doping on the sensitivity of SnO2 thin film sensors

SnO2 thin films were deposited on thermally oxidized Si substrates by RF magnetron sputtering. The sensing properties of pure, Pt-doped, Pd-doped, and Pt/Pd co-doped SnO2 thin films were investigated for two gases, CO and CH4. Pd was added to the bulk of SnO2 thin film to induce the Fermi energy control effect while Pt was doped on the surface of SnO2 thin film for the spillover effect. When 50 Angstrom Pt was co-doped on the surface of SnO2 thin film with 0.5 wt% Pd added to the bulk, the maximum sensitivities were obtained for both the gases at 350degreesC due to the contribution of the two different mechanisms.