Temperature effects on dislocation core energies in silicon and germanium

TL;DR

This study investigates how temperature influences the free energies and stability of dislocation core structures in silicon and germanium using non-equilibrium methods and Monte Carlo simulations, highlighting vibrational entropy and anharmonic effects.

Contribution

It introduces a combined approach of non-equilibrium methods and Monte Carlo simulations to analyze temperature effects on dislocation core energetics in semiconductors.

Findings

Vibrational entropy increases free energy differences between reconstructions.

Double-period reconstruction becomes more stable at high temperatures.

Anharmonic effects significantly influence defect structures at elevated temperatures.

Abstract

Temperature effects on the energetics of the 90-degree partial dislocation in silicon and germanium are investigated, using non-equilibrium methods to estimate free energies, coupled with Monte Carlo simulations. Atomic interactions are described by Tersoff and EDIP interatomic potentials. Our results indicate that the vibrational entropy has the effect of increasing the difference in free energy between the two possible reconstructions of the 90-degree partial, namely, the single-period and the double-period geometries. This effect further increases the energetic stability of the double-period reconstruction at high temperatures. The results also indicate that anharmonic effects may play an important role in determining the structural properties of these defects in the high-temperature regime.