  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.
