Effect of van der Waals interactions on the stability of SiC polytypes

TL;DR

This study uses density functional theory with van der Waals corrections to analyze SiC polytypes, confirming that the 3C-SiC is the most stable form and showing how vdW interactions influence stability and electronic structure.

Contribution

It demonstrates the importance of including van der Waals interactions in DFT calculations to accurately predict SiC polytype stability and electronic properties.

Findings

vdW interactions significantly affect polytype stability

3C-SiC is confirmed as the most stable polytype

vdW effects are more sensitive to cubic sites

Abstract

Density functional theory calculations with a correction of the long-range dispersion force, namely the van der Waals (vdW) force, are performed for SiC polytypes. The lattice parameters are in good agreement with those obtained from experiments. Furthermore, the stability of the polytypes in the experiments, which show 3C-SiC as the most stable, are reproduced by the present calculations. The effect of the vdW force on the electronic structure and the stability of polytypes are discussed. We observe that the vdW interaction is more sensitive to the cubic site than the hexagonal site. Thus, the influence of the vdW force increases with decreasing the hexagonality of the polytype, which results in the confirmation that the most stable polytype is 3C-SiC.