Cross-sectional TEM study of unepitaxial crystallites in a homoepitaxial diamond film

Abstract We investigated the structure of unepitaxial crystallites (UC; non-epitaxial crystallites) in homoepitaxial diamond films on Ib (001) diamond substrate grown by the chemical vapor deposition (CVD), employing field emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HRTEM). The UC was classified into two types depending on the orientation relationship to the homoepitaxial film; one rotates by 70.5° around the common 〈110〉 axis, corresponding to Σ3 coincidence site lattice (CSL) relation. The other type does not have any particular angular relationship. It was found that the growth of the former type is closely related to a lattice dislocation on the substrate surface as well as the homoepitaxial film. On the other hand, there was hardly any lattice dislocation observed at the bottom of the latter type. A nanometer-sized crystalline diamond particle was observed at the nucleation site of the latter one.