A study on the electrodeposition mechanism of cobalt-nickel/copper multilayer from sulfate solution

The cobalt-nickel/copper multilayer films were prepared by electrodeposition process in sulfate solution using a three electrode cell. Cyclic voltammetry and double chronoampermetry techniques were utilized to characterize the multilayer system and to obtain the nucleation and growth mechanism. The cyclic voltammograms determined the reduction potential range of the three components and also clearly emphasized that electrodeposition of cobalt-nickel alloy was controlled by a kinetic process, while copper ions were reduced with diffusion-controlled mechanism. These results were confirmed with those which were extracted from the chronoampermetry curves. In addition, the current transients revealed that nucleation mechanism was a typical three-dimensional nucleation process. The Atomic Force Microscope images (AFM) of these multilayers also confirmed the three-dimensional nucleation mechanism. The compositional analysis of these multilayers was carried out by Atomic Absorption Spectroscopy (AAS) and X-ray Photoelectron Spectroscopy (XPS) methods. The bulk and surface compositional analysis both revealed that the amount of Copper component within the cobalt-nickel layers is less than 3%.