Slope analysis and scaling analysis of electrodeposited thin films

Kinetic Monte Carlo simulation of polycrystalline silver metal electrodeposition: scaling of roughness and effects of deposition parameters

In this work, a kinetic Monte Carlo (KMC) technique was used to simulate the growth morphology of electrodeposited polycrystalline Ag thin films under a galvanostatic condition (current density). The many-body Embedded Atom Method (EAM) potential has been used to describe the Ag-Ag atomic interaction. Herein, the surface morphology is affected by the kinetic diffusion of adatoms where four jump processes are considered, namely hopping, exchange, step-edge exchange and grain boundary. The results have shown that the surface roughness follows a power law behavior versus film thickness (∝L^α) and time (∝t^β), with the roughness and growth exponents α and β found to be α = 1.14 ± 0.01 and β = 0.57 ± 0.01. The surface morphology under different deposition parameters (current density and substrate temperature) has been discussed in detail. The surface roughness increases where the current density increases due to high deposition rates, which can accelerate the growth of island mode, especially on the (111) surface. In contrast, the surface roughness decreases the temperature of the substrate increases due to thermal agitation, allowing to transform nearly columnar grains to grains with a flat and smooth surface. Finally, the simulations provided information on the subsurface deposition rate of each grain that is not directly available for experimental investigations. It was observed that the (111) grain has a faster deposition rate compared to the (100) and (110) grains due to the low surface energy of the (111) grain.

Morphological stabilization and KPZ scaling by electrochemically induced co-deposition of nanostructured NiW alloy films

We have assessed the stabilizing role that induced co-deposition has in the growth of nanostructured NiW alloy films by electrodeposition on polished steel substrates, under pulsed galvanostatic conditions. We have compared the kinetic roughening properties of NiW films with those of Ni films deposited under the same conditions, as assessed by Atomic Force Microscopy. The surface morphologies of both systems are super-rough at short times, but differ at long times: while a cauliflower-like structure dominates for Ni, the surfaces of NiW films display a nodular morphology consistent with more stable, conformal growth, whose height fluctuations are in the Kardar-Parisi-Zhang universality class of rough two-dimensional interfaces. These differences are explained by the mechanisms controlling surface growth in each case: mass transport through the electrolyte (Ni) and attachment of the incoming species to the growing interface (NiW). Thus, the long-time conformal growth regime is characteristic of electrochemical induced co-deposition under current conditions in which surface kinetics is hindered due to a complex reaction mechanism. These results agree with a theoretical model of surface growth in diffusion-limited systems, in which the key parameter is the relative importance of mass transport with respect to the kinetics of the attachment reaction.