Authors: S.S. Roy, R. McCann, P. Papakonstantinou, G.A. Abbas and J.A. McLaughlin
Affilation: University of Ulster, United Kingdom
Pages: 797 - 799
Keywords: Tetrahedral carbon, NEXAFS, Ultrathin, Raman
The ta-C films with thickness in the range of 1-10 nm were obtained by FCVA and investigated by NEXAFS and Raman spectroscopies. The C=C bonds were quantitatively determined from the area of pi* peak in the C-K edge of NEXAFS spectra. It was clearly revealed that the relative concentration of C=C bonds is similar with film thickness above 2 nm. Evidence of the surface defects was established on films 1 nm thick. The C K edge NEXAFS analysis further showed that the content of the surface defect (mainly C–H bonds) decreased with the increase thickness (Fig. 1). <br> <br>Raman parameters such as G peak width, ID/IG ratio, critically analyzed in terms of film thickness. The intensity of the Raman G peak increased with film thickness (Fig. 2). The ta-C film, showed a very small changes in baseline slope in the entire ultra thin region with the DLC component dominating, which suggests superior film properties. <br> <br>In this study we demonstrate that the combined study of normalized Raman and NEXAFS spectra is very useful in determining the role of thickness in the structure of ta-C films.