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

Resistance characteristics of thin film sensors based on uncoated SnO
₂
, SnO
₂
with CuO overlayer and SnO
₂
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 SnO
₂
thin film sensors. Conversion of molecular oxygen (O
₂

^-
) to atomic oxygen (O
^-
) is shown to reduce the concentration of charge carriers in the conduction band of SnO
₂
film. Co-existence of a greater amount of adsorbed oxygen on the SnO
₂
film surface in conjunction with modulation of the space-charge region at the CuO-SnO
₂
interface are attributed to influence the resistance of the sensor structures under reducing gas.