Dynamic formation of spherical voids crossing linear defects

TL;DR

This paper presents a model and simulations for the evolution of spherical voids in porous germanium layers during annealing, highlighting their role in dislocation network reconfiguration and defect removal.

Contribution

It introduces a predictive model for void shape evolution during thermal treatment, combining simulations and experiments to understand defect dynamics in porous materials.

Findings

Large spherical voids align along dislocation cores.

Void formation facilitates dislocation network reconfiguration.

Thermally activated processes help reduce defect energy.

Abstract

A predictive model for the evolution of porous Ge layer upon thermal treatment is reported. We represent an idealized etched dislocation core as an axially symmetric elongated hole and computed its dynamics during annealing. Numerical simulations of the shape change of a completely spherical void via surface diffusion have been performed. Simulations and experiments show individual large spherical voids, aligned along the dislocation core. The creation of voids could facilitate interactions between dislocations, enabling the dislocation network to change its connectivity in a way that facilitates the subsequent annihilation of dislocation segments. This confirms that thermally activated processes such as state diffusion of porous materials provide mechanisms whereby the defects are removed or arranged in configurations of lower energy. This model is intended to be indicative, and more detailed experimental characterization of process parameters such as annealing temperature and time, and could estimate the annealing time for given temperatures, or vice versa, with the right parameters.