Diamond-like carbon films from a hydrocarbon helium plasma

A coated substrate produced by depositing a diamond-like carbon film onto a substrate utilizing a plasma-enhanced chemical vapor deposition process which comprises the steps of (a) admixing acetylene and helium to form a gas mixture;

• (b) providing a plasma chamber containing a substrate;
• and (c) introducing said acetylene/helium gas mixture into said chamber wherein a diamond-like carbon film is deposited on said substrate, said diamond-like carbon film having an optical density in the range from about 1 to about 3 at a wavelength from about 200 run to about 365 nm and is thermally stable at temperature of about 590.degree. C.

A structure comprising:

• (a) a transparent substrate having a surface;
• and
• (b) a layer of carbon on said surface wherein said layer of carbon contains hydrogen, has an optical density in the range from about 1 to about 3 at a wavelength from about 200 nm to about 365 nm and is thermally stable temperatures of about 590.degree. C.