Ellipsometric studies of the oxidation kinetics of Cu particles supported on oxidised Si(100)

The oxidation of Cu particles supported on oxidised Si(100) by molecular oxygen was investigated by means of ellipsometry and Auger electron spectroscopy. The oxidation between 373 and 673 K of three different particle sizes was investigated: 4, 5 and 15 nm particles respectively. The δΔ curves of oxidation were divided into a part corresponding to surface oxidation, oxidation of the particles from Cu to Cu2O and oxidation from Cu2O to CuO0.67. All measured δΔ curves scaled in the exposure, indicating a first order dependence on the oxygen pressure. The following activation energies for the oxidation from Cu to Cu2O were obtained: Eact = 28 ± 5 kJ/mol for 4 nm, Eact = 30 ± 5 kJ/mol for 5 nm and Eact = 25 ± 5 kJ/mol for 15 nm particles. For the oxidation of Cu2O to CuO0.67: Eact = 38 ± 4 kJ/mol for 4 nm, Eact = 36 ± 4 kJ/mol for 5 nm and Eact = 37 ± 4 kJ/mol for 15 nm particles.