Direct visualization and characterization of chemical bonding and phase composition of grain boundaries in polycrystalline diamond films by transmission electron microscopy and high resolution electron energy loss spectroscopy

Polycrystalline diamond films are composed of diamond grains, interconnected by grain boundaries of ill defined nature. In this study we characterized the local phase composition, chemical bonding, and structure of the grain boundaries by electron energy loss spectroscopy (EELS) in the plasmonic and core-level ragimes, using a monochromated and high resolution transmission electron microscope. Peaks at 283.5, 286.3, and 287.5 eV in the C(1s) pre-edge structure provide direct evidence for the preferential presence of amorphous carbon and hydrogen bonding at grain boundaries. Plasmonic EELS reveals a high amorphous carbon component in the grain boundaries region. (C) 2011 American Institute of Physics. [doi:10.1063/1.3660582]