Studies of atom beams produced by a saddle field source used for depositing diamond-like carbon films on glass

A saddle field cold cathode source was used to produce diamond-like carbon (DLC) coatings on glass substrates by dissociation and ionisation of acetylene in a low pressure vacuum. Langmuir probe investigations of the ion current density and plasma potentials showed the existence of a positive potential barrier at a distance of 100 mm from the source with an ionisation degree of up to 80% in the carbon flux in the near source region and less than 15% ionisation at larger distances. Film deposition rate, density and morphology were studied as a function of the geometrical arrangement of the samples. The feasibility of producing DLC films with good uniformity on insulating materials at distances more than 150 mm was shown. The films with a thickness of 1.8 μm, hardness 4000 HK and optical band gap of about 1 eV were deposited on glass substrates at a distance of 300 mm above the source.