Morphological and synchrotron X-ray microdiffraction studies of large columnar CVD diamond crystallites

Optical microscopic and goniometric measurements were combined with microra diography, diffraction-pattern analysis and topography to study a 2 mm thic k [001]-texture CVD (chemical vapour deposition) diamond film that had deve loped a coarse-grained structure composed of separate columnar crystallites . Individual columns were capped by large (001) facets, with widths up to 0 .5 mm, and which were smooth but not flat, whereas the column sides were mo rphologically irregular. The refractive deviation of X-rays transmitted thr ough the crystallites was exploited for delineating facet edges, thereby fa cilitating the controlled positioning of small-cross-section X-ray beams us ed for recording diffraction patterns from selected volumes in two represen tative crystallites. Their structure consisted of a [001] axial core column surrounded by columns in twin orientation with respect to the core. The di amond volume directly below the (001) facets was free from low-angle bounda ries, and no dislocation outcrops on the facets were detected. Significant elastic deformation of this volume was only present close to the facet peri phery. where misorientations reached a few milli-radians. Lattice imperfect ion was high in the twins with similar to 1 degrees misorientations.