Collective formation of misfit dislocations at the critical thickness for equilibrium nanowire heterostructures

TL;DR

This paper models how strain energy evolves in heterostructure nanowires, revealing a critical thickness where collective misfit dislocation formation causes a sudden transition from elastic to relaxed states, using a novel finite element simulation.

Contribution

It introduces a finite element modeling technique that captures the collective formation of misfit dislocations and identifies the critical thickness for relaxation in heterostructure nanowires.

Findings

Dislocation network formation occurs abruptly at a specific critical thickness.

The transition from elastic to relaxed configuration involves a characteristic misfit density.

The modeling approach incorporates both elastic and plastic relaxation mechanisms.

Abstract

In this work we model the evolution of strain energy during different growth stages of heterostructure nanowires. We find that the minimum energy configuration changes abruptly from fully elastically strained to partially relaxed due to collective formation of a misfit dislocation network. The transition at the critical thickness is associated with a characteristic density of misfits. These insights are gained from a technique developed to simulate misfit dislocations in a finite element framework, incorporating both elastic and plastic relaxation in a stationary heterostructure. We argue that these results have general relevance for mismatched heterostructures.