Characterization of the core structure of growth defects in CVD diamond films by UHREM: Z-shaped twin interactions

We report here recent electron microscopy observations of defect core struc tures in diamond thin films prepared by microwave plasma-assisted chemical vapour deposition (CVD) on silicon substrates. The, defects have been ident ified by ultra-high resolution electron microscopy (UHREM) at 0.15nm resolu tion. These results clearly reveal the core structure of two particular fau lt systems arising from the zig-zag shaped interaction between three nanotw in lamellae, with the occurrence of one as yet unreported structural unit o f octagonal type. We analyse the UHREM images of these complex defect confi gurations and we propose plausible 3D models for each of them, on the basis of image-matching with computer simulations. The identification of these d efect structures with growth defects provides valuable insights into the me chanisms involved in the CVD production of diamond films.