Oriented sp2 bonded carbon structure of hydrogenated amorphous carbon films

Abstract

Hydrogenated amorphous carbon films consist of sp 2 or sp 3 bonded carbon networks and hydrogen terminations, and their structure are often determined in terms of sp 2 / sp 3 ratio and the hydrogen contents. Although sp 3 bonded carbon structure is isotropic, sp 2 bonded carbon structure has structural anisotropy. To detect the orientation of extremely small the sp 2 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 sp 2 bonded carbon networks were detected from their incident angle dependence on XAS and XES spectra. The continuity of these oriented sp 2 carbon bonded structures was small and formed extremely small clusters, and the orientation distribution and direction of the sp 2 carbon structure depended on the source material. Some films have different sp 2 orientations on the surface and inside the film. The orientation of this sp 2 bonded carbon structure in the film was also an important factor and may affect several other film properties. • There is hydrogenated amorphous carbon films with sp 2 oriented structure. • The sp 2 oriented structure could be estimated by angle dependence of XAS and XES. • The sp 2 orientation angle is depend on deposition condition of the films. • The orientation of sp 2 bonded carbon structure affects film properties.