Crossover from compact to branched films in electrodeposition with surface diffusion

Area of Science:

• Materials Science
• Surface Science
• Computational Physics

Background:

• Thin film electrodeposition is vital for creating functional materials.
• Instabilities during deposition can lead to complex, branched structures.
• Understanding the interplay between adsorption, reduction, and diffusion is key to controlling film morphology.

Purpose of the Study:

• To develop and analyze a computational model for thin film electrodeposition.
• To investigate the competition between instability development and surface relaxation.
• To predict the conditions leading to compact layer formation versus branched growth.

Main Methods:

• Computer simulations of cation movement, adsorption, and surface diffusion.
• Analysis of a model incorporating activated surface diffusion with hop attempts (G) and detachment probability (ε).
• Application of a scaling approach based on the Villain-Lai-Das Sarma equation.

Main Results:

• Formation of a compact wetting layer followed by branched deposit growth.
• Maximal wetting layer thickness (z_c) increases with G, but is weakly affected by ε.
• Scaling prediction z_c∼G^γ (γ≈0.43) accurately describes the transition to unstable growth.

Conclusions:

• The model successfully predicts thin film morphology based on deposition parameters.
• Wetting layer thickness is primarily controlled by hop attempts (G), offering a route to tunable film structures.
• The findings have implications for fabricating multifunctional structures with controlled porosity.