Spiral growth and step edge barriers.

Area of Science:

• Surface science
• Materials science
• Crystallography

Background:

• Two-dimensional nucleation and spiral growth are key mechanisms in thin film deposition.
• Understanding atomic incorporation is crucial for controlling thin film morphology.
• The Pt(111) surface serves as a model system for studying epitaxial growth.

Purpose of the Study:

• To compare the growth dynamics of spiral mounds with screw dislocations to wedding cake structures formed by 2D nucleation.
• To investigate the influence of step-edge barriers on large-scale structure formation.
• To elucidate the atomic incorporation mechanisms governing different growth modes.

Main Methods:

• Phase field simulations were employed to model crystal growth.
• Homoepitaxial growth experiments were conducted on the Pt(111) surface.
• Analysis focused on the impact of suppressed interlayer transport on structure evolution.

Main Results:

• Both spiral mounds and wedding cake structures exhibit similar large-scale shapes under conditions of significant step-edge barriers.
• The Pt(111) surface demonstrates that suppressed interlayer transport is key to achieving these similar morphologies.
• Spiral mounds show a higher vertical growth rate due to distinct atomic incorporation at the top region.

Conclusions:

• Step-edge barriers play a critical role in determining the large-scale morphology of epitaxial growth.
• The observed growth behaviors can be explained by an enhanced apparent step-edge barrier model.
• This study provides insights into controlling thin film structures through manipulation of growth conditions.