Photon enhanced chemical vapor deposition of carbon based thin films from toluene vapor

The photon enhanced deposition of amorphous carbon films from toluene vapor condensed on a cooled substrate was investigated. In particular the dependence on the photon energy was studied. The photon energy is selected by changing the filter; pyrex (below 3.2 eV), quartz (below 7.5 eV) and LiF (below 11 eV). For the pyrex determined photon range a film is grown with a low growth rate in spite of the large number of photons incident on the condensed toluene. This film shows no detectable vibrational absorptions. In the intermediate quartz determined photon range with photon energies above the dissociation threshold the deposition rate is significantly larger (35 nm/hour) and shows two prominent absorption peaks attributed to olefinic CH2 groups. If the LiF determined photon range is added, with photon energies partly above the ionization threshold, the deposition rate is again increased to 95 nm/hour despite the small number of photons which are added by changing to the LiF range. In these films, several vibrational absorptions are present dominated by those of CH2.