Effect of density and thickness on H2-gas sensing property of sputtered SnO2 films

Undoped and Pd-doped SnO2 films were deposited under various conditions for the investigation of the effect of Pd doping, porosity, and thickness on their H2 gas sensing properties. The temperature of the substrate and the pressure of the discharge gas were varied. All films formed were composed of columns with thicknesses between 20 and 30 nm. The film density decreased as the discharge gas pressure increased and the substrate temperature decreased. It showed values between 4.2×103 and 7.0×103 kg/m3 depending on the deposition condition. Low film density and Pd doping resulted in high sensitivity and fast response. The largest sensitivity was observed for a Pd-doped film with a low density of 4.7×103 kg/m3 and a thickness of 20 nm.