Ab initio study of the migration of intrinsic defects in 3C-SiC

TL;DR

This study uses ab initio density functional theory to analyze the migration mechanisms of intrinsic defects in 3C-SiC, highlighting the dominant role of interstitials over vacancies in diffusion processes.

Contribution

It provides detailed insights into defect migration pathways and the relative mobility of vacancies and interstitials in 3C-SiC using first-principles calculations.

Findings

Interstitials are more mobile than vacancies.

Silicon vacancy metastability suppresses its diffusion.

Interstitials significantly influence dopant diffusion.

Abstract

The diffusion of intrinsic defects in 3C-SiC is studied using an ab initio method based on density functional theory. The vacancies are shown to migrate on their own sublattice. The carbon split-interstitials and the two relevant silicon interstitials, namely the tetrahedrally carbon-coordinated interstitial and the <110>-oriented split-interstitial, are found to be by far more mobile than the vacancies. The metastability of the silicon vacancy, which transforms into a vacancy-antisite complex in p-type and compensated material, kinetically suppresses its contribution to diffusion processes. The role of interstitials and vacancies in the self-diffusion is analyzed. Consequences for the dopant diffusion are qualitatively discussed. Our analysis emphasizes the relevance of mechanisms based on silicon and carbon interstitials.