Spiral Growth and Step Edge Barriers

TL;DR

This paper compares spiral mounds with wedding cakes in epitaxial growth, showing they share similar large-scale shapes under certain conditions, and investigates how step edge barriers influence growth dynamics.

Contribution

It demonstrates that spiral mounds and wedding cakes develop similar shapes when step edge barriers suppress interlayer transport, highlighting the role of barriers in growth morphology.

Findings

Spiral mounds and wedding cakes attain similar shapes with significant step edge barriers.

Spiral mounds exhibit higher vertical growth rates due to different atom incorporation mechanisms.

An enhanced apparent step edge barrier explains the increased vertical growth of spiral mounds.

Abstract

The growth of spiral mounds containing a screw dislocation is compared to the growth of wedding cakes by two-dimensional nucleation. Using phase field simulations and homoepitaxial growth experiments on the Pt(111) surface we show that both structures attain the same characteristic large scale shape when a significant step edge barrier suppresses interlayer transport. The higher vertical growth rate observed for the spiral mounds on Pt(111) reflects the different incorporation mechanisms for atoms in the top region and can be formally represented by an enhanced apparent step edge barrier.