Native oxidation of sputter deposited polycrystalline copper thin films during short and long exposure times: Comparative investigation by specular and non-specular grazing incidence X-ray absorption spectroscopy

Thin copper-oxide layers formed on Cu-metal due to the exposure to ambient air at short and long timescales were investigated by means of reflection mode grazing incidence X-ray absorption spectroscopy under specular and non-specular conditions. The quantitative evaluation of near edge X-ray absorption, as well as specular and non-specular EXAFS data measured for various different grazing angles show that the oxide film is best described by a model structure consisting of a duplex type oxide layer with an outer layer of CuO in contact with the gas atmosphere and an inner Cu2O layer at the interface to the underlying Cu-metal.