Microstructural analysis of atomistic models of Si-rich amorphous silicon–germanium alloys

Microstructural analysis of nanostructured amorphous silicon–germanium alloys: Numerical modeling

“…On the other hand, the Vegard's law underestimates the amorphous alloy density, in agreement with experimental findings [5,10,25]. We retrieve here practically the same results as those obtained for structural models with homogeneous random distribution of Ge atoms as well as with Ge-atoms segregation [19]. The macroscopic mass density is thus insensitive to the compositional heterogeneity in amorphous silicon-germanium alloy.…”

“…(2) and (3) [19]. A nanoporous paracrystalline model for a-Si was first constructed from a 980-atom diamond structure with four nanopores of~1 nm in diameter and one paracrystallite of~1.6 nm in diameter.…”

“…We are interested particularly in the effect of compositional heterogeneities on the structural properties of a-Si 1 − x Ge x alloy in comparison with the ideal case, that of a homogeneous random distribution of the atoms. In our previous work [19] we have envisaged atomistic models of a-Si 1 − x Ge x alloy with nanoscale Ge-segregation. We have concluded that such phase-segregation must be discarded, in agreement with Tzoumanekas and Kelires [16] finding.…”

Small-Angle X-Ray Scattering of Amorphous Germanium: Numerical Modeling

“…The force constants α 0 and β 0 are treated as empirical parameters; they have been fixed at their crystalline values 42.09 N·m −1 and 5.72 N·m −1 , respectively [34]. The total strain energy given by Equation (1) was minimized by an iterative conjugate gradient method.…”

“…A simple phenomenological model describing the dependence of f on the scattering vector for Ge atom is available [34], viz. :…”