Study of synchrotron radiation near-edge X-ray absorption fine-structure of amorphous hydrogenated carbon films at various thicknesses

Abstract

The compositions and bonding states of the amorphous hydrogenated carbon films at various thicknesses were evaluated via near-edge X-ray absorption fine-structure (NEXAFS) and elastic recoil detection analysis combined with Rutherford backscattering spectrometry. The absolute carbon sp 2 contents were determined to decrease to 65% from 73%, while the hydrogen contents increase from 26 to 33 at.% as the film thickness increases. In addition, as the film thickness increases, the π (C=C), σ (C-H), σ (C=C), and σ (C≡C) bonding states were found to increase, whereas the π (C≡C) and σ (C-C) bonding states were observed to decrease in the NEXAFS spectra. Consequently, the film thickness is a key factor to evaluate the composition and bonding state of the films.