Modeling of nonequilibrium surface growth by a limited-mobility model with distributed diffusion length

Area of Science:

• Materials Science
• Surface Science
• Computational Physics

Background:

• Kinetic Monte Carlo (KMC) simulations are standard for studying surface morphology in molecular beam epitaxy (MBE).
• Limited mobility (LM) models offer simplified simulations but often use a fixed diffusion length, limiting their accuracy.

Purpose of the Study:

• To investigate an extended LM model with a variable diffusion length to better understand diffusional processes in MBE growth.
• To improve the accuracy of LM models by incorporating stochasticity in particle diffusion.

Main Methods:

• Developed an extended LM model based on the Das Sarma-Tamborena model, featuring a variable diffusion length.
• Introduced fluctuations to the diffusion length by sampling from a Gaussian distribution for each adsorbed particle.
• Compared simulation results with KMC simulations on 1D and 2D substrates across different growth regimes.

Main Results:

• Deviations between the extended LM model and KMC simulations were resolved by adding diffusion length fluctuations.
• Diffusional fluctuations significantly impact cluster properties during submonolayer growth and surface profiles in multilayer growth.
• The enhanced LM model can generate surface morphologies indistinguishable from KMC simulations under various growth conditions.

Conclusions:

• Incorporating stochastic fluctuations in diffusion length is crucial for accurately modeling surface morphology in MBE.
• The enhanced LM model provides a computationally efficient alternative to KMC simulations for predicting growth structures.