4H-SiC/6H-SiC interface structures studied by high-resolution transmission electron microscopy

The interface structures of 4H-SiC/6H-SiC heterostructures formed in monocrystalline bulk silicon carbide were studied by high-resolution electron microscopy of cross-sectional specimens. The samples were grown on the (0001̄) C face of a 6H-SiC seed with in situ Ce doping. The observed transition region is atomically flat over regions of several hundreds nm. The transition from the initial 6H-SiC growth to the 4H-SiC growth happens all at once at certain thicknesses with the occurrence of only a few layers of 4H-SiC (6H-SiC) before (after) the transition. The atomic stacking sequence at the interface of the two polytype crystals can be resolved.