Near-Edge X-ray Absorption Fine Structure of Hard Carbon Film Formed by Gas Cluster Ion Beam Assisted Deposition

Abstract

The coordination of the carbon atoms in the diamond-like carbon (DLC) films formed by Ar gas cluster ion beam (GCIB) assisted deposition of fullerene was investigated using synchrotron radiation. Near-edge x-ray absorption fine structure (NEXAFS) spectra of the carbon K-edge of the DLC films formed by various methods were measured over the excitation energy range 275-320 eV, using synchrotron radiation. On the basis of the analysis of the peak corresponding the transition of the excitation electron from carbon 1s orbital to π* orbital, relative sp 2 contents of various DLC films were determined. The DLC films formed by Ar GCIB assisted fullerene deposition were found to consist of a high sp 3 hybridized carbon.

NEXAFS study on the local structures of DLC thin films formed by Ar cluster ion beam assisted deposition

“…This indicated that the sp 2 content of the DLC film formed by RF plasma was larger than those of the DLC films produced by the GCIB assisted deposition as reported in ref. [3]. For comparison between NEXAFS spectra of the DLC films produced by the GCIB assisted deposition, the width of C 1s → π* resonance increased with the substrate temperature.…”

“…The estimation procedure of sp 2 content from NEXAFS was described in the previous paper [3]. The amount of sp 2 bonded carbon atoms can be extracted by normalizing the area of the resonance corresponding to 1s→π* transitions at 285.3 eV with the area of a large section of the spectrum.…”

“…The experimental apparatus and procedures employed in the present study were identical to those in our previous study [3]. The synchrotron radiation dispersed by a constant-deviation constant-length spherical grating monochromator was perpendicularly irradiated to the surface of sample film.…”

“…For the optimization of deposition conditions for the development of high-quality DLC films, a rapid and reliable evaluation method was demanded. In the previous work, we measured the NEXAFS spectra of carbon K-edge of some DLC films using synchrotron radiation [3]. The sp 2 content of DLC film produced by the GCIB method was found to be lower than those by other methods.…”

“…Mechanical and electronic properties of carbon material are related to the coordination of the carbon atoms in films. The DLC films with a high content of sp 3 hybridized carbon, that is a low content of sp 2 hybridized carbon, have been used by taking advantage of their high hardness. Therefore, the sp 2 content is the most important information for understanding the properties of the DLC film.…”