Investigation of nanocrystalline cobalt films electrodeposited at different current densities

Abstract

In this paper, a study has been performed of nanocrystalline cobalt films electrodeposited at different current densities in the range from 40 to 50 mA/cm2. The films were thick (about 40 µm) and were prepared from a cobalt sulfate solution with pH value of 4.5 at room temperature. Suitable values for cobalt film deposition potential were chosen on the basis of the recorded cyclic voltammograms. The chemical composition on the surface of the films was investigated by X-ray photoelectron spectroscopy. The morphological structure of the films was made visible with scanning electron microscopy. As the current density was increased, the amount of cracks, nodules and cavities on the surface of the films were observed to be larger, due to increased tensile stress in the films. The morphological structure was composed of irregular, densely packed grains with sizes mainly in the range of 50–100 nm. The average grain size decreased with increasing current density.