XPS study of the oxidation of a Cu-Cd thin film

The oxidation of a Cu-Cd thin film obtained by coevaporation of the two metals has been studied by XPS. The oxygen is initially adsorbed on the alloy surface, afterwards the Cd component is oxidized to CdO, while the Cu component remains unchanged also at high exposure of O2 (6 × 108 L). The Cu/Cd atomic ratio decreases during the oxidation reaction, in agreement with the formation of a CdO layer onto the alloy surface. The thickness of the oxidized layer has been quantified as a function of O2 exposure. © 1991.