Investigation of Si/3C-SiC interface properties using classical molecular dynamics

Abstract

Molecular dynamics simulations were carried out for different structural models of the Si/3C-SiC interface using the Tersoff SiC potential that can model both Si and SiC. We find that the bonding at the Si/3C-SiC interface has a strong effect on the crystallization of the Si phase and that a degree of intermixing is present between the two materials with some C atoms migrating from the 3C-SiC (hereinafter referred to as SiC) into the Si region. The degree of intermixing is likely to exhibit a strong dependence on the temperature and most likely also increases with time, which would lead to changes in the Si/SiC interface during the life of the Si/SiC composite. The inter-mixing also creates disorder and defects of threefold and fivefold bonded atoms in the vicinity of the interfaces. In particular, {111}12⟨110⟩ misfit dislocations were formed at all three types of interfaces [(100), (110), and (111)] in order to relieve the local stress due to lattice mismatch. Additionally, the Si(110)/SiC(110) and Si(111)/SiC(111) interfaces prepared at higher temperatures show the formation of the {111}16⟨112⟩ partial dislocation which arises due to intrinsic stacking faults. We find that the bonding at the crystalline(c) c-Si/SiC interface is weaker than that in bulk crystalline Si, whereas bonding at the amorphous(a)-Si/SiC interface is stronger than that in amorphous Si. Therefore, the rupture in the yield stress occurs at the vicinity of the Si/SiC interface and in the Si region for the a-Si/SiC systems, respectively. Finally, for both bulk and Si/SiC interface systems, a strong variation of the yield strength with temperature was observed.