Oriented sp2 bonded carbon structure of hydrogenated amorphous carbon films

Hydrogenated amorphous carbon films consist of sp2 or sp3 bonded carbon networks and hydrogen terminations, and their structure are often determined in terms of sp2/sp3 ratio and the hydrogen contents. Although sp3 bonded carbon structure is isotropic, sp2 bonded carbon structure has structural anisotropy. To detect the orientation of extremely small the sp2 bonded carbon network structure in hydrogenated amorphous carbon film, X-ray absorption spectroscopy (XAS) and X-ray emission spectroscopy (XES) measurements using synchrotron radiation X-rays with different incident angles were performed. On all prepared films from three types of hydrocarbon source, and the oriented sp2 bonded carbon networks were detected from their incident angle dependence on XAS and XES spectra. The continuity of these oriented sp2 carbon bonded structures was small and formed extremely small clusters, and the orientation distribution and direction of the sp2 carbon structure depended on the source material. Some films have different sp2 orientations on the surface and inside the film. The orientation of this sp2 bonded carbon structure in the film was also an important factor and may affect several other film properties.