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

We investigated the structure of unepitaxial crystallites (UC non-epitaxial crystallites) in homoepitaxial diamond films on lb (001) diamond substrate grown by the chemical vapor deposition (CVD), employing field emission sca nning electron microscopy (FE-SEM) and high-resolution transmission electro n microscopy (HRTEM). The UC was classified into two types depending on the orientation relationship to the homoepitaxial film; one rotates by 70.5 de grees around the common < 110 > axis, corresponding to Sigma3 coincidence s ite lattice (CSL) relation. The other type does not have any particular ang ular relationship. It was found that the growth of the former type is close ly related to a lattice dislocation on the substrate surface as well as the homoepitaxial film. On the other hand, there was hardly any lattice disloc ation observed at the bottom of the latter type. A nanometer-sized crystall ine diamond particle was observed at the nucleation site of the latter one. (C) 2001 Elsevier Science B.V. All rights reserved.