Amorphous oxygen-containing hydrogenated carbon films formed by plasma enhanced chemical vapor deposition

Abstract

Films were deposited from glow discharge plasmas of acetylene-oxygen-argon mixtures in a deposition system fed with radio frequency power. The principal variable was the proportion of oxygen in the gas feed, X ox. The chemical structure and elemental composition of the films were investigated by transmission infrared spectrophotometry and x-ray photoelectron spectroscopy. Optical properties-refractive index, absorption coefficient, and optical gap-were determined from transmission ultraviolet-visible spectroscopy data. The latter also allowed the determination of film thicknesses and hence deposition rates. It was found that the oxygen content of the films and, within limits, the refractive index are controllable by the selection of X ox .

Plasma enhanced chemical vapor deposition of titanium (IV) ethoxide–oxygen–helium mixtures

“…Oxygen to carbon atomic ratios of 0.14 and 0.08, respectively, were observed in films obtained by the PECVD of mixtures of benzene and helium [40], and of acetylene and argon [35], which are similar to that measured in the present study (0.17) for the film with R ox = 0%.…”

“…6 are very similar to those obtained from films produced by the PECVD of acetylene-oxygenargon mixtures [35]. Significant differences are observed, however, from the spectrum of a film deposited from an acetylene-argon mixture.…”

Controlled fluorination of a-C:F:H films by PECVD of ethylene–hexafluorobenzene mixtures

“…As described below, however, XPS confirms the presence of some oxygen, probably bonded to carbon. A stretching absorption characteristic of C-O groups typically appears at about 1200 cm − 1 , and a band of carboxyl groups at 1700 cm − 1 is also observed in IR spectra of oxygenated plasma polymers [23]. Neither band is clearly present in the spectra taken of films at low R F ; at higher R F it is unclear if there is a contribution from these species since these peaks are very close to others due to fluorinated groups (1160 cm − 1 , CF 2 symmetric stretch; 1718 cm − 1 , F 2 CfC and 1781 cm − 1 , F 2 CfCF).…”

Semi-empirical modeling of the optical gap of amorphous hydrogenated nitrogenated carbon films

“…16 Typically the optical gap would then be obtained from plots of (␣nE) 1/2 vs E, which show a linear region. Therefore, following the example of other investigators, 17 we have defined the optical gap as the photon energy corresponding to ␣ϭ10 4 cm Ϫ1 .…”