DESCRIPTION OF THE ELECTRONIC DENSITY-OF-STATES OF A-C-H FILMS WITH LOW AND HIGH OPTICAL GAPS

In order to obtain information about the density and energy distributi on of the pi states introduced by the sp(2) carbon sites in hydrogenat ed amorphous carbon (a-C:H) films, we have combined X-ray (XPS) and ul traviolet (UPS) photoelectron spectroscopy experiments with optical me asurements in the 0.5-6 eV spectral range. Attention has also been pai d to plasmon losses from both XPS and optical data. The results obtain ed on two series of a-C:H films prepared by the same plasma technique but presenting different optical gaps (2.9 and 1.6 eV respectively) ar e compared and discussed in relation to the sample microstructure.