XPS and Raman analyses of films composition evidenced that layers synthesized in 0.5 or 1 mbar CH4 had the highest sp3 content, ~30% more than films synthesized in vacuum or 10 mbar CH4. However, their hardness was lower than 15 GPa and the elastic modulus indicated a plastic behavior. The samples with lower sp3 content were quite hard materials and possessed a higher elastic modulus compared to films synthesized in CH4 (200 vs. 75 GPa). Based on density and carbon hybridization ratio, the films synthesized in vacuum were assessed to be a-C type of DLC, while films synthesized in CH4 seem to belong to the a-C:H category.