Epitaxial interfaces between crystallographically mismatched materials

TL;DR

This paper introduces a novel mechanism for forming epitaxial interfaces between materials with mismatched lattices, involving out-of-plane tilting to achieve a balanced coincidence-site lattice, supported by theoretical and experimental validation.

Contribution

It presents a new model explaining epitaxial interface formation between mismatched materials, validated by first-principles calculations and experimental data.

Findings

The proposed model accurately predicts interface formation.

First-principles calculations agree with experimental observations.

The mechanism involves out-of-plane tilting to optimize lattice coincidence.

Abstract

We report an unexpected mechanism by which an epitaxial interface can form between materials having strongly mismatched lattice constants. A simple model is proposed in which one material tilts out of the interface plane to create a coincidence-site lattice that balances two competing geometrical criteria---low residual strain and short coincidence-lattice period. We apply this model, along with complementary first-principles total-energy calculations, to the interface formed by molecular-beam epitaxy of cubic Fe on hexagonal GaN and find excellent agreement between theory and experiment.