Heteroepitaxial diamond films on silicon (001): Interface structure and crystallographic relations between film and substrate

The interfaces between highly (001)-oriented diamond films and the silicon (001) substrates were investigated by high-resolution electron microscopy. It was found that heteroepitaxially oriented grains which exhibit a defined orientation relationship to the substrate lattice grow directly on the clean silicon surface. The majority of the grains observed have their basic axes parallel or almost (within a few degrees) parallel to the basic axes of silicon. In addition, grains with about 14°and 70°rotation around a 110 axis are also observed. In the latter case the lattice is in twin relation to that of the ideally oriented nonrotated grains. In all cases the interface structure is well defined and the angular deviation of the two lattices is compensated by appropriate interface dislocations. These dislocations are either of the 60°type or are Lomer dislocations formed by the reaction of two types of 60°dislocations. The observed orientation relationships can be explained on the basis of the near-coincidence-site lattice of the two materials.