Time-dependent evolution of the structure and chemical bonds in diamond-like carbon films generated by the hot filament chemical vapour deposition method

Abstract The chemical structure of inhomogeneous amorphous carbon films grown for different lengths of time in a hot filament chemical vapour deposition reactor from a methane-hydrogen mixture has been investigated by electron energy loss spectroscopy (EELS) and Raman spectroscopy. The changes in EELS and Raman spectral shapes allowed us to monitor the time-dependent structural evolution of the films, from an amorphous lattice with a noticeable fraction of sp 3 -bonded hydrogenated carbon atoms to a prevalence of microcrystalline graphitic domains. The depth profile of hydrogen in the grown film for 120 min has been measured by the 1 H( 15 N, αγ) 12 C nuclear reaction analysis technique. The low value of the hydrogen content (less than 4 at.%) is consistent with the structure of this carbon film which has a density of 1.9 g cm -3 . By the combined use of Rutherford backscattering spectrometry and nuclear reaction analysis the mean carbon coverage thickness was found to be 22±5 nm. Secondary ion mass spectrometry measurements confirmed this conclusion.