Quantitative REELS of amorphous carbon and carbon nitride films

Abstract

The dielectric properties of amorphous carbon (a-C) and carbon nitride in the 3 to 80 eV energy range were determined by quantitative analysis of reflection electron energy-loss spectroscopy (REELS) spectra of these films. The energy loss function (ELF) of each material has been obtained by a trial-and-error procedure, when a good quantitative agreement between the simulated and experimental electron inelastic cross-sections at three different primary energies (i.e. 0.5, 1 and 1.5 keV) is achieved. Kramers-Kronig transformation is then used to obtain the dielectric function. The loss functions of a-C and CN x are characterized by two main features which result from collective excitations of the p and the p + s electrons, respectively. The incorporation of nitrogen in the amorphous carbon matrix is discussed in terms of changes in the dielectric function.