Effect of Soft X-ray Irradiation on Film Properties of a Hydrogenated Si-Containing DLC Film

The effect of soft X-ray irradiation on hydrogenated silicon-containing diamond-like carbon (Si-DLC) films intended for outer space applications was investigated by using synchrotron radiation (SR). We found that the reduction in film thickness was about 60 nm after 1600 mA center dot h SR exposure, whereas there was little change in their elemental composition. The reduction in volume was attributable to photoetching caused by SR, unlike the desorption of hydrogen in the case of exposure of hydrogenated DLC (H-DLC) film to soft X-rays. The ratio of the sp(2) hybridization carbon and sp(3) hybridization carbon in the hydrogenated Si-DLC films, sp(2)/(sp(2) + sp(3)) ratio, increased rapidly from similar to 0.2 to similar to 0.5 for SR doses of less than 20 mA center dot h. SR exposure significantly changed the local structure of carbon atoms near the surface of the hydrogenated Si-DLC film. The rate of volume reduction in the irradiated hydrogenated Si-DLC film was 80 times less than that of the H-DLC film. Doping DLC film with Si thus suppresses the volume reduction caused by exposure to soft X-rays.

Automated summary

Soft X-ray irradiation on hydrogenated silicon-containing diamond-like carbon films results in thickness reduction and changes in local carbon atom structure without altering elemental composition. Doping with silicon suppresses volume reduction caused by exposure to soft X-rays in DLC films.