Theoretical study of dislocation nucleation from simple surface defects in semiconductors

TL;DR

This study uses atomistic simulations to analyze how simple surface defects in semiconductors influence dislocation nucleation and plastic deformation, revealing temperature-dependent mechanisms and the role of surface defect structures.

Contribution

It provides a theoretical framework for predicting dislocation nucleation from surface defects in semiconductors using atomistic calculations.

Findings

Surface defects weaken atomic structure, initiating dislocations.

Dislocation character depends on shear stress and Peierls stress.

High temperature leads to amorphization and melting zones.

Abstract

Large-scale atomistic calculations, using empirical potentials for modeling semiconductors, have been performed on a stressed system with linear surface defects like steps. Although the elastic limits of systems with surface defects remain close to the theoretical strength, the results show that these defects weaken the atomic structure, initializing plastic deformations, in particular dislocations. The character of the dislocation nucleated can be predicted considering both the resolved shear stress related to the applied stress orientation and the Peierls stress. At low temperature, only glide events in the shuffle set planes are observed. Then they progressively disappear and are replaced by amorphization/melting zones at a temperature higher than 900 K.