Electron spectroscopy study of plasma assisted amorphous carbon deposition

We report the results of a study of the electronic structure of carbon-base d thin films deposited by a RF plasma. A novel cylindrical plasma configura tion has been used to grow amorphous hydrogenated carbon films. Electrons w ithin a low pressure, two-temperature plasma are constrained to oscillate b etween two electrodes and ionize methane/hydrogen mixtures. The ions that f orm are near room temperature. They drift out of the trap region to deposit on a substrate located beyond the electrodes. The underlying strength of t his configuration rests in the ability to control several plasma parameters independently: the flux, energy, and the ratio of the charged to neutral p articles leaving the plasma, and the chemical species being deposited. Adju sting these parameters alters the density of the film being grown, its hydr ogen content, and the film's porosity and morphology. Films of thickness up to 10 mum have been grown on flat substrates and on cylindrical plastic mi cro spheres. The electronic structure properties of this material has been studied via X-ray photoemission spectroscopy (XPS) and electron energy loss spectroscopy. The thus-obtained films show primarily a-C:H character. (C) 2000 Elsevier Science S.A. All rights reserved.