Effect of Adsorbate Diffusion on the Dendritic Morphology of Electrodeposited Films

We study the formation of deposits with dendritic morphology using numerical simulations of a model of electrodeposition and diffusion of the adsorbed material. The model considers a diffusive flux of cations in solution, the instantaneous adsorption and reaction in contact with the film surface, and random walks of mobile atoms on that surface, with a maximum of G hops per atom and a detachment probability e per neighbor at the current position. For low temperature or large current, which correspond to small G, the deposits are similar to diffusion-limited aggregates growing from the flat electrode; for high temperature or very small current, which are represented by large G or e, the deposits have thick rounded columns with sporadic ramification. In these conditions, the growth direction is controlled by the orientation of the electrode and of the cation flux. For balanced conditions of adsorbate diffusion and current (typically 102 ≤ G ≤ 104 and e ≤ 0.1, but also for larger G and very small e), the fil...