Strain distribution in zincblende and wurtzite GaAs nanowires bent by a one-sided (In, Al)As stressor shell: consequences for torsion, chirality, and piezoelectricity

TL;DR

This paper develops a finite-strain model to analyze large deformations in bent GaAs nanowires with heterostructures, revealing how strain distribution affects torsion, chirality, and piezoelectric effects.

Contribution

It introduces a nonlinear strain model coupled with finite element analysis to map strain fields in heterostructured nanowires, highlighting the impact of shear strain on mechanical and piezoelectric properties.

Findings

Bending is mainly determined by ε_zz strain component.

Shear strain differences influence transverse piezoelectric fields.

Strain distribution varies between zincblende and wurtzite nanowires.

Abstract

We present a finite-strain model that is capable of describing the large deformations in bent nanowire heterostructures. The model incorporates a nonlinear strain formulation derived from the first Piola-Kirchhoff stress tensor, coupled with an energy functional that effectively captures the lattice-mismatch-induced strain field. We use the finite element method to solve the resulting partial differential equations and extract cross-sectional maps of the full strain tensor for both zincblende and wurtzite nanowires with lattice-mismatched core and one-sided stressor shell. In either case, we show that the bending is essentially exclusively determined by $\varepsilon_{zz}$. However, the distinct difference in shear strain has important consequences with regard to both the mechanical deformation and the existence of transverse piezoelectric fields in the nanowires.