Correlation between a-C:H film properties and Ar/CH4 dielectric barrier discharge

A dielectric barrier discharge (DBD) in Ar/CH4 gas mixtures used for amorphous hydrogenated carbon (a-C:H) film deposition was investigated. It was found that the a-C:H film properties (the ratios of sp3/sp2 and CH3/CH2, the number density of hydrogen atoms in the film and the energy band gap) correlate with the number densities of Ar(1s5) atom and CH(X2Π) radical. A high value of the energy band gap, which corresponds to a high content of sp3 fraction in the film was obtained, when the CH radical number density in the plasma was relatively small (∼ 108 cm− 3). The DBD breakdown voltage decreased when the a-C:H film was deposited on the dielectric surface of the electrode.