Heterocrystalline SiC: Ab initio calculations for the interface structure of combinations of cubic and hexagonal SiC

We present the results of ab initio DFT-LDA pseudopotential calculations of structural and electronic properties of heterocrystalline combinations of cubic and hexagonal SiC, which are chemically identical but structurally different materials. The structural rearrangement of atoms along the hexagonal axis at the interface is taken into account. The resulting superlattices possess indirect gaps which are smaller than the presently known smallest one of 3C-SiC. The relationship of electron or hole confinement and polytype arrangement is explicitly derived for a zinc-blende/wurtzite combination. The existence of electronic interface states is carefully studied.