Characterization and optical properties of diamondlike carbon prepared by electron cyclotron resonance plasma

Diamondlike carbon (DLC) films have been prepared on radio-frequency (rf) b iased substrates maintained at low temperature using electron cyclotron res onance CH4-Ar plasma. The effects of negative rf bias and reactant gas comp osition on the bonding structure, hardness, and resistivity of the films we re systematically investigated. DLC films deposited on PMMA (polymethyl met hacrylate) were examined by optical methods to determine the absorption coe fficients and the optical band gap. It was found that DLC films synthesized at bias voltage of -(80-100) V and F-CH4/F-Ar of 0.075-0.086 exhibit extre me hardness of more than 3000 kgf mm(-2), high electrical resistivity up to 10(14) Omega cm, band gap larger than 2.5 eV, and excellent optical transp arency. The results indicate that ECR CH4-Ar plasma with low negative rf bi as and suitable CH4/Ar gas ratio can process optically transparent and hard protective DLC films on PMMA plastics.