The effect of hydrogen addition in argon-acetylene plasma on the structure of amorphous carbon films

Amorphous carbon films were formed on nickel/silicon (100) substrates by plasma jet chemical vapor deposition (PJCVD). The carbon films were deposited at atmospheric pressure using an argon-acetylene and argon-hydrogen-acetylene plasma. The plasma composition was analyzed by optical emission spectroscopy (OES). The results indicated that the dominant species in the argon-acetylene and argon-hydrogen-acetylene plasmas were the CH radical and C2 particles. The emission intensities of CH and C2 lines depended on the hydrogen amount in plasma and the distance. Scanning electron microscopy analysis demonstrated that the surface roughness of the coatings decreased with the addition of hydrogen and the increase of distance from 5 mm to 7 mm. The oxygen concentration increased with the increase of the deposition distance. The Raman spectroscopy results indicated that the addition of the hydrogen in the argon-acetylene plasma lead to the formation of nano-crystalline graphite films at 5 mm distance. The increase of the distance from 5 mm up to 7 mm stipulated the formation of multiphase SiC/carbon films when the argon-hydrogen-acetylene ratios were 100:2.4:1 and 100:1.2:1.