Effect of Hydrogen on Flaking of Carbon Films on Mo and W

Flaking of carbon film was studied by depositing hydrogen doped carbon. lms on tungsten and molybdenum substrates. Topographies of the carbon coatings were analyzed with scanning electron microscopy and three-dimension profilometer. Secondary ion mass spectrometry and Raman spectra analysis was used to determine the hydrogen concentration and the number of sp(3) bonds in the. lms, respectively. Carbon film properties varied from tetrahedral amorphous carbon (ta-C) to hard hydrogenated amorphous carbon (a-C: H). Carbon coatings hold large residual stresses, which are released during or after deposition. Typical stress relief patterns were observed. In most samples buckling started at some dislocation or at the edge of the film and adhesion energy was deduced from the sizes of the stress relief patterns. It was observed, that carbon. lms were more adherent to tungsten than to molybdenum and that codeposited hydrogen had a significant effect to flaking propagation in the carbon films.