Enhanced oxygen adsorption activity by CuO catalyst clusters on SnO2 thin film based sensors

Resistance characteristics of thin film sensors based on uncoated SnO₂, SnO₂ with CuO overlayer and SnO₂ with CuO dotted clusters are compared in three different backgrounds of air, oxygen and vacuum. Measurements for the three sensor configurations are carried out as a function of temperature. The novel dispersal method of CuO catalyst in the form of dotted clusters is seen to enhance the oxygen adsorption activity on surface of SnO₂ thin film sensors. Conversion of molecular oxygen (O₂ ^-) to atomic oxygen (O^-) is shown to reduce the concentration of charge carriers in the conduction band of SnO₂ film. Co-existence of a greater amount of adsorbed oxygen on the SnO₂ film surface in conjunction with modulation of the space-charge region at the CuO-SnO₂ interface are attributed to influence the resistance of the sensor structures under reducing gas.