Neutral silicon interstitials in silicon carbide: a first principles study

Ting Liao (1, 2) , Guido Roma (2) , Jingyang Wang (1)

1 High-Performance Ceramic Division
2 Service de Recherches de Métallurgie Physique

Abstract. The structures and stability of single silicon interstitials in their neutral state are investigated via first principles calculations in 3C- and 4H-SiC. By carefully checking the convergence with Brillouin Zone (BZ) sampling and supercell size we explain the disagreement between previous published results and we show that the split interstitial along <110> direction and tetrahedrally carbon coordinated structure have similar formation energies in the cubic polytype. A new migration mechanism for the silicon interstitial in the neutral state is presented here which could be important for the evolution of defect populations in SiC. For 4H-SiC, the most energetically favourable silicon interstitial is found to be the split interstitial configuration ISisp<110> but situated in the hexagonal layer. The defect formation energies in 4H-SiC are in general larger than those in 3C-SiC, implying that the insertion of silicon interstitial introduces a large lattice distortion to the local coordination environments and affect even the second- or third-nearest neighbours. We also present a comparison between well converged plane waves calculations and calculations with three localized orbital basis sets; one of them, in spite of providing a reasonable description for bulk properties, is clearly not suitable to describe interstitial defects.

Mots clés: Physical Sciences

Ting Liao, Guido Roma, Jingyang Wang. Neutral silicon interstitials in silicon carbide: a first principles study. Philosophical Magazine, 2009, 89 (26), pp.2271-2284. ⟨10.1080/14786430903055184⟩. ⟨hal-00514031⟩