Optical and Mechanical Properties of Hard Hydrogenated Amorphous Carbon Films Deposited by Plasma CVD

Abstract
Hydrogenated amorphous carbon (a-C:H) films were deposited by plasma chemical vapor deposition from pure CH4 at a low pressure of the order of 10-4 Torr under a magnetic field to confine the plasma on negatively self-biased electrode. The reflectance spectra were measured in a wide range of 0.5–25 eV by using synchrotron radiation and a usual light source. The dielectric constants were determined by applying the Kramers-Kronig relation. Using an effective medium approximation, volume fractions of diamondlike, graphitelike and polymeric (polyethylene) components were derived. These results were compared with Raman scattering, hydrogen contents and Vicker's hardness of the asdeposited and annealed films.