EN
In this study amorphous hydrogenated carbon films (a-C:H) were formed on Si (111) from an Ar-C_2H_2 and Ar-C_2H_2-H_2 gas mixtures at 1000 Pa pressure using a plasma jet chemical vapour deposition. It is shown that by varying the Ar:C_2H_2 ratio and adding the hydrogen gas in plasma, the structure, surface morphology, growth rate of the coatings, and consequently their optical properties can be controlled.