Effect of high substrate bias and hydrogen and nitrogen incorporation on spectroscopic ellipsometric and atomic force microscopic studies of tetrahedral amorphous carbon films

The influence of substrate bias and hydrogen/nitrogen incorporation on the optical properties [studied by spectroscopic ellipsometry (SE)] and surface morphology [studied by atomic force microscopy] of tetrahedral amorphous carbon (ta-C) films, deposited by S bend filtered cathodic vacuum arc (FCVA) process, is reported. SE spectra of the imaginary part of the dielectric constant are used to estimate carbon bonding ratios. In ta-C films, optical constants increase with substrate bias and hydrogen/nitrogen incorporation. The optical band gap (Eg) and sp3 content increase up to −200 V substrate bias and then decrease. Eg increases with hydrogen incorporation but is unchanged by nitrogen incorporation.