Critical thickness and radius for axial heterostructure nanowires using finite-element method

Area of Science:

• Materials Science
• Nanotechnology
• Computational Physics

Background:

• Heterostructured nanowires are crucial for advanced electronic and optoelectronic devices.
• Understanding critical thickness for misfit dislocations is vital for controlling nanowire growth and properties.
• Existing models often simplify strain field interactions, potentially limiting accuracy.

Purpose of the Study:

• To simulate and determine the critical thickness for misfit dislocation generation in heterostructured nanowires on compliant substrates.
• To investigate the influence of nanowire radius on critical thickness.
• To refine models by incorporating the interaction between initial coherent strain and dislocation-induced strain fields.

Main Methods:

• Utilized finite-element methods (FEM) for three-dimensional simulation.
• Employed an overall energy balance approach to calculate critical thickness.
• Simulated strain fields from misfit dislocations and their interaction with initial coherent strain.
• Calculated total residual strain energy based on local residual strain.

Main Results:

• A radius-dependent critical thickness for misfit dislocation generation was identified.
• Critical thickness approaches infinity for nanowire radii below a specific critical value.
• The model accurately predicts simulated results, aligning well with experimental data.
• The calculated critical radius is smaller than predicted by models neglecting strain field interactions.

Conclusions:

• The study provides a more accurate prediction of critical thickness by considering complex strain field interactions.
• The findings offer valuable insights for the design and fabrication of high-quality heterostructured nanowires.
• This work advances the understanding of strain relaxation mechanisms in nanostructures.