The role of a graphitic surface layer in electron-stimulated ordering in tetrahedral amorphous carbon films

Electron-stimulated graphitic ordering in tetrahedral amorphous carbon (ta-C) films was found to be affected by the removal of the graphitic surface layer present in as-deposited films. To remove the graphitic layer on ta-C films fabricated by the filtered cathodic vacuum arc method, the sample was etched with oxygen plasma. The removal of the surface layer was examined by transmission electron energy loss spectroscopy, surface-enhanced Raman spectroscopy, and surface-sensitive X-ray absorption spectroscopic measurements. The electron-stimulated graphitization was retarded in oxygen plasma etched samples presumably owing to the lack of graphitic nuclei for heterogeneous nucleation.