Core reconstruction of the 90-degree partial dislocation in non-polar semiconductors

TL;DR

This study compares the energetics of single-period and double-period core reconstructions of 90-degree partial dislocations in non-polar semiconductors C, Si, and Ge, revealing the double-period structure's lower energy due to strain balance.

Contribution

It demonstrates that the double-period core reconstruction is energetically more favorable across multiple semiconductors, highlighting the strain mechanisms involved.

Findings

Double-period structure has lower energy than single-period.

Double-period introduces smaller bond-length deviations.

Balance of strain components explains energy differences.

Abstract

We investigate the energetics of the single-period and double-period core reconstructions of the 90-degree partial dislocation in the homopolar semiconductors C, Si, and Ge. The double-period geometry is found to be lower in energy in all three materials, and the energy difference between the two geometries is shown to follow the same trends as the energy gap and the stiffness. Both structures are fully reconstructed, consisting entirely of fourfold coordinated atoms. They differ primarily in the detail of the local strains introduced by the the two reconstructions in the core region. The double-period structure is shown to introduce smaller average bond-length deviations, at the expense of slightly larger average bond-angle bending distortions, with respect to the single-period core. The balance between these two strain components leads to the lower energy of the double-period reconstruction.