Experiment research on the double-layer diamond-like carbon film prepared by double laser beams

A femtosencond laser and a nanosecond laser were used to ablate the graphite target in the oxygen atmosphere and high vacuum respectively, and two kinds of diamond-like carbon films were prepared on the silicon substrates. Then their optical constants were estimated by fitting the infrared transmissivity curves. Double-layer diamond-like carbon film with different thickness combinations on the silicon samples were designed and prepared:the layer deposited by femtosencond laser in the oxygen atmosphere was taken as the infrared anti-reflective layer because of its low refractive index and high transmissivity; the layer deposited by nanosecond laser in the high vacuum was taken as the protective layer based on its high hardness and corrosion resistance. The tests show that transmissivity of the samples in the medium infrared band decreases by 0.5%~3% and the surface hardness of the samples increases by 7.2-24.7 GPa when the thickness of the protective layer increases. Results of the corrosion resistance tests show that the protective layer has the well corrosion resistance, but it can not prevent the alkaline liquor from soaking into the deeper depth to corrupt the lower anti-reflective layer if the thickness of the protective layer is very thin. The research result can offer the experiment basis for the designs of double-layer or multi-layer films in the different fields.