First principles determination of the Peierls stress of the shuffle screw dislocation in silicon

TL;DR

This study uses density functional theory to accurately calculate the Peierls stress of a specific screw dislocation in silicon, analyzing boundary condition effects and dislocation core paths.

Contribution

First principles calculations of the Peierls stress for silicon's screw dislocation, comparing supercell and cluster models to determine a reliable stress range.

Findings

Peierls stress range: 2.4 x 10^-2 to 2.8 x 10^-2 eV/Å^3

Dislocation prefers the {111} plane, avoiding the higher energy {100} plane

Boundary conditions significantly affect stress estimates

Abstract

The Peierls stress of the a/2<110> screw dislocation belonging to the shuffle set is calculated for silicon using density functional theory. We have checked the effect of boundary conditions by using two models, the supercell method where one considers a periodic array of dislocations, and the cluster method where a single dislocation is embedded in a small cluster. The Peierls stress is underestimated with the supercell and overestimated with the cluster. These contributions have been calculated and the Peierls stress is determined in the range between 2.4 x 10-2 and 2.8 x 10-2 eV {\AA}-3. When moving, the dislocation follows the {111} plane going through a low energy metastable configuration and never follows the 100 plane, which includes a higher energy metastable core configuration.