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

Abstract

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