The Effect of Nonequilibrium Synthesis Conditions on the Structure and Optical Properties of Amorphous Carbon Films

Amorphous carbon (a-C) thin films are synthesized using a nonequilibrium method of ion-plasma sputtering of a graphite target under argon atmosphere at a constant plasma current. The local structure of carbon films is studied by the Raman spectroscopy method. Using the normal distribution in the decomposition of the Raman spectra, it is found that a peak typical for a phonon density of states with sp(3) bond hybridization appears in the frequency region of 1260 cm(-1) at synthesis temperatures of less than 150 degrees C. In addition, the influence of the dimensions of nanostructures composed of sp(2) sites on the width of optical bandgap and their correlation with the results of X-ray photoelectron spectroscopy (XPS) in a-C films is shown.