First-principles study on Si(−220)/6H–SiC(0001) interface

A periodical structure with low lattice mismatch at Si(−220)/6H–SiC(0001) interface has been confirmed by HRTEM. Corresponding to the observed interface structure, the first-principles calculations based on the density functional theory are employed to understand the bonding mechanism of the surface states. It is shown that the combination of Si with C-terminated 6H–SiC surface is more stable than that with Si-terminated surface, but a strong fold caused by considerable interaction of C-2p and Si-3p states at the interface with C-termination may introduce a high density of structural defects in the subsequently epitaxial Si film. Meanwhile, relaxation energy of the interface with C-terminated 6H–SiC surface is bigger than that with Si-terminated surface. It means that it is easier to deposit Si films in (−220) orientation on Si-faced 6H–SiC(0001) substrates at a relative low temperature.