Island mobility and dynamic scaling during thin film deposition

Simulation results for island nucleation and growth during thin film deposition with mobile islands are presented. The islands have a diffusion constant Ds^-μ that depends on island size s. The dynamic scaling properties of the island density variation with coverage are investigated. It is found that the maximum density Nₘ~(D/F)^-χ occurs at coverage θₘ~(D/F)^-ω where F is the monomer deposition rate. The growth exponents {χ} and {ω} are found to vary in a systematic way with the mobility coefficient {μ}. This suggests that experiments may be devised to investigate this behavior in real systems. A mean-field-theory description is also presented to draw out the physics of the scaling. Numerical solutions of the rate equations show very good agreement with the simulation results and also show that the scaling phenomenon is robust with respect to island morphology and is not restricted to the simplistic model used here in the simulations.