EELS ANALYSIS OF HYDROGENATED DIAMOND-LIKE CARBON-FILMS

Electron energy-loss spectroscopy (EELS) has been used to analyze the structure of hydrogenated diamond-like carbon (DLC) films deposited by plasma-assisted CVD (PACVD) under a variety of conditions. Spectra ob tained from highly oriented pyrolytic graphite and amorphous carbon we re used as references. The ratio sp(3) (tetragonal) to sp(2) (trigonal ) carbon sites in the DLC films was quantified for different hydrogen contents from the near-edge structure (ELNES) of the carbon K-edge and compared with a constrained network structure model. The results were in agreement with this model and showed an increase of the ratio sp(3 ) to sp(2) with increasing hydrogen content in the material. The irrad iation damage caused by the electron beam increased the sp(2) fraction even when using a N-2-cooled specimen holder. In order to better iden tify the chemical bonding from the carbon K near-edge structure, the f irst two peaks of the edge were deconvoluted to obtain the peaks of in dividual transitions, after subtracting the simulation of the carbon K -edge continuum to extract the core-excitation peaks. The relative con tributions of ls/pi (C=C), ls/sigma *(C-H) and ls/sigma *(C-C) were t hus obtained. The position in energy of each peak is discussed. (C) 19 98 Published by Elsevier Science S.A.