THE DYNAMICS OF MORPHOLOGICAL INSTABILITY DURING ELECTRODEPOSITION

Mullins-Sekerka morphological stability theory is applied to analyze the possible factors affecting the evolution of roughness and protrusions. The analysis introduces, for the first time, a damping factor which determines whether the diffusion layer thickness is affected by the surface perturbations. The results show that increasing the reacting-ion concentration and concentration gradient at the electrode-solution interface and decreasing the diffusion layer thickness and surface concentration favor morphological instability. The effect of ionic migration within the diffusion layer is also considered. The analysis indicates that the concentration gradient at the interface is the main deposition parameter controlling the morphology of the deposit. In the extreme case, when the diffusion layer thickness is smaller than the wave-length of the surface perturbation, the diffusion layer follows the perturbed surface, and the electrodeposition becomes stable.