Undissociated screw dislocations in silicon: calculations of core structure and energy

TL;DR

This study investigates the core structure and stability of screw dislocations in silicon using classical potentials and first-principles calculations, clarifying the most stable configurations and the role of hybridization.

Contribution

It demonstrates that the most stable screw dislocation core in silicon is in the 'shuffle' set, clarifies the dependence on potential models, and explores hybridization effects in the core.

Findings

The most stable core is in the 'shuffle' set, not 'glide'.

Stability depends on the classical potential used.

Metastable configurations involve sp2 hybridization.

Abstract

The stability of the perfect screw dislocation in silicon has been investigated using both classical potentials and first-principles calculations. Although a recent study by Koizumi et al . stated that the stable screw dislocation was located in both the 'shuffle' and the 'glide' sets of {111} planes, it is shown that this result depends on the classical potential used, and that the most stable configuration belongs to the 'shuffle' set only, in the centre of one hexagon. We also investigated the stability of an sp 2 hybridization in the core of the dislocation, obtained for one metastable configuration in the 'glide' set. The core structures are characterized in several ways, with a description of the three-dimensional structure, differential displacement maps and derivatives of the disregistry.