Copper oxides formation by a low pressure RF oxygen plasma

Copper foils are exposed at low pressure (200 Pa) to an inductively coupled oxygen plasma which is also examined spectroscopically to identify the major reactive species. The metal surface is oxidized and the resulting oxides are identified by optical methods: FTIR, photoluminescence and UV-Visible-NIR diffuse reflectance spectroscopies. The following oxides were characterized: a precursor oxide CuxO of mixed valency character, copper (I) oxides (Cu2O, Cu3O2) and copper (II) oxide CuO. The nature of the oxidized layer and its thickness depend on the time of exposure to the plasma and on the working conditions.