Influence of the surface morphology on the early stages of Cu oxidation

The growth and morphological features of Cu films deposited on NaCl(1 0 0) by e-beam evaporation have been examined to evaluate the effect of various surface morphologies on the initial oxidation of Cu. It is shown that epitaxial Cu films with significantly reduced surface roughness can be achieved by first nucleating Cu seeds at 450 °C that favors epitaxial Cu grains which is followed by subsequent seed growth at 150 °C that favors smooth Cu film. The effect of the variations of the surface morphology of the resulting Cu films by the different growth conditions on the early stages oxidation of Cu films is examined by in situ transmission electron microscopy (TEM) and ex situ atomic force microscopy (AFM). It is shown that the changes in the surface morphologies of the Cu film result in distinct variations in the nucleation density and growth rates of oxide islands. Such correlation between the surface morphology and the initial oxidation behavior of the Cu films provides insights into understanding the microscopic processes of the transient oxidation of metals and for manipulating the initial oxide formation through surface treatments.