Theoretical study of the recombination of Frenkel pairs in irradiated silicon carbide

TL;DR

This paper uses first principles calculations to study how Frenkel pairs in irradiated silicon carbide recombine, identifying mechanisms and activation energies consistent with experiments.

Contribution

It provides a detailed theoretical analysis of recombination mechanisms and energy barriers for Frenkel pairs in 3C-SiC using first principles methods.

Findings

Recombination mechanisms include interstitial migration, atom exchange, and concerted displacements.

Activation energies range from 0.65 eV to 1.84 eV, matching experimental data.

Vibrational contributions to free energy barriers are negligible.

Abstract

The recombination of Frenkel pairs resulting from low energy recoils in 3C-SiC has been investigated using first principles and Nudged Elastic Band calculations. Several recombination mechanisms have been obtained, involving direct interstitial migration, atoms exchange, or concerted displacements, with activation energies ranging from 0.65 eV to 1.84 eV. These results are in agreement with experimental activation energies. We have determined the lifetime of the $V_{Si}+Si_{TC}$ Frenkel pair, by computing phonons and the Arrhenius prefactor. The vibrational contributions to the free energy barrier have been shown to be negligible in that case.