Defect Formation and Kinetics of Atomic Terrace Merging

TL;DR

This paper models the defect formation during atomic terrace merging on metal surfaces, using a kinetic approach mapped to a 1-D random sequential adsorption problem, providing insights into defect control and surface evolution.

Contribution

It introduces a kinetic model for step doubling defects, analytically solves it via mapping to a 1-D RSA problem, and explores defect control through a key dimensionless parameter.

Findings

Defect fraction increases linearly with parameter deviation near q=1

Final surface state can be reached faster with fewer defects by parameter variation

Model accurately captures surface morphology evolution

Abstract

Pairs of atomic scale terraces on a single crystal metal surface can be made to merge controllably under suitable conditions to yield steps of double height and width. We study the effect of various physical parameters on the formation of defects in a kinetic model of step doubling. We treat this manifestly non- equilibrium problem by mapping the model onto a 1-D random sequential adsorption problem and solving this analytically. We also do simulations to check the validity of our treatment. We find that our treatment effectively captures the dynamic evolution and the final state of the surface morphology. We show that the number and nature of the defects formed is controlled by a single dimensionless parameter $q$. For $q$ close to one we show that the fraction of defects rises linearly with $\epsilon \equiv 1-q$ as $0.284 \times \epsilon$. We also show that one can arrive at the final state faster and with fewer defects by changing the parameter with time.