Thin film growth by 3D multi-particle diffusion limited aggregation model: Anomalous roughening and fractal analysis

• Published in: Physica A Vol. 493; pp. 135 - 147
• Main Authors: Nasehnejad, Maryam, Nabiyouni, G., Gholipour Shahraki, Mehran
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-03-2018
• Subjects: Anomalous scaling; Electrodeposition; Fractal dimension; Multi-particle diffusion limited aggregation (DLA) model; Surface roughness; Electrodeposition; Surface roughness; Fractal dimension; Anomalous scaling; Multi-particle diffusion limited aggregation (DLA) model
• ISSN: 0378-4371; 1873-2119
• DOI: 10.1016/j.physa.2017.09.099

In this study a 3D multi-particle diffusion limited aggregation method is employed to simulate growth of rough surfaces with fractal behavior in electrodeposition process. A deposition model is used in which the radial motion of the particles with probability P, competes with random motions with probability 1−P. Thin films growth is simulated for different values of probability P (related to the electric field) and thickness of the layer(related to the number of deposited particles). The influence of these parameters on morphology, kinetic of roughening and the fractal dimension of the simulated surfaces has been investigated. The results show that the surface roughness increases with increasing the deposition time and scaling exponents exhibit a complex behavior which is called as anomalous scaling. It seems that in electrodeposition process, radial motion of the particles toward the growing seeds may be an important mechanism leading to anomalous scaling.
The results also indicate that the larger values of probability P, results in smoother topography with more densely packed structure. We have suggested a dynamic scaling ansatz for interface width has a function of deposition time, scan length and probability. Two different methods are employed to evaluate the fractal dimension of the simulated surfaces which are “cube counting” and “roughness” methods. The results of both methods show that by increasing the probability P or decreasing the deposition time, the fractal dimension of the simulated surfaces is increased. All gained values for fractal dimensions are close to 2.5 in the diffusion limited aggregation model.
•A 3D multi-particle diffusion limited aggregation method is employed to simulate growth of rough surfaces in electrodeposition process.•The simulated surfaces exhibit a complex behavior which is called as anomalous scaling.•The values of H and β that have been measured by this model are close to KPZ universality class.•A dynamic scaling ansatz is suggested for interface width as a function of thickness, scan length and probability P.•The values of H=0.45,βloc=0.46,β=0.35,(H∕β)=1.29,δ=0.16,γ=0.14 and y=0.05 are found for characteristic scaling exponents.