Mechanical properties and deformation mechanisms of surface-modified 6H-silicon carbide

The effect of amorphous film on the deformation mechanism and mechanical properties of 6H-SiC were systematically explored by a combination of both experiments and molecular dynamic (MD) simulations in nanoindentation. The experimental results showed that the plastic deformation of surface-modified 6H-SiC is mainly accommodated by dislocation activities in the subsurface and an amorphous layer with uniform thickness. The MD results indicated that the amorphous layer on the surface of the residual indentation mark consists of both amorphous SiO₂ and SiC due to direct amorphization. In addition, the amorphous SiO₂ film undergoes densification and then ruptures with the indentation depth increases. The modulus and hardness increase with increasing the indentation depth at the initial stage but will reach their stable values equivalent to monocrystalline 6H-SiC.