Study on Deposition Phenomena of Hydrogenated Carbon films in Glow Discharge by Optical Emission Spectroscopy

Abstract

The carbon films were deposited on the cathode surface in the D. C. glow discharge with the Ar-CH₄ and H₂-CH₄ gas mixtures. We analyzed the optical emission spectra from the glow discharge plasma, and the cathode surface by FT-IR and XPS after the discharge. The relationship between the optical emission spectra and the deposition behavior on the cathode surface was investigated., The emission intensity of hydrogen atoms in the H₂-CH₄ glow discharge was strongly observed, and the deposited carbon films in this plasma contained many hydrogen atoms bonding chemically with carbon atoms. Thus, it was found that the composition of the deposited carbon films was strongly related to the chemical species in the glow plasma. In the Ar-CH₄ glow discharge, however, the emission intensities decreased in the CH₄ % range above 1.5 %. This is probably because the metastable argon atoms quenched by CH₄ molecules and the discharge characteristics largely changed. In the case of H₂-CH₄ glow discharge, the emission intensity ratio CH 431.4/H I 656.3 increased with an increase of the deposited carbon. Therefore, it is possible to estimate the quantity of the deposited carbon by monitoring the emission intensity ratio.