Cross-sectional hydrogen content and mass density profiles of DLC film by neutron and X-ray reflectivity

Ozeki, Kazuhide*; Yonemura, Masao*; Masuzawa, Toru*; Saito, Hidetoshi*; Ogoe, Yasuharu*; Hirakuri, Kenji*; Takeda, Masayasu  

Hydrogen content in the DLC film is very important factor because it greatly influences on its mechanical properties and microstructure such as hardness, wear resistance, surface roughness, and sp3/sp2 ratio. In the present study, we prepared the DLC film using plasma CVD technique varying H/CH ratio from 0 to 9. Cross-sectional hydrogen content and mass density profiles of the films were defined by neutron and X-ray reflectivity measurements, and the results were compared with that from ERDA analysis. And O/C atomic ratio of the oxide layer of the film surface was also analyzed using XPS. From the neutron and X-ray reflectivity analysis, hydrogen content and mass density in the DLC film increased with film depth from the surface, and average hydrogen content showed more than 30 % in all films. By combining with XPS results, it is clarified that hydrogen content in the surface layer was lower than that in bulk layer.