Characterisation of a saddle field source for deposition of diamond-like carbon films

A saddle field cold cathode source was used to produce diamond-like carbon (DLC) coatings 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 100 mm from the source with an ionisation rate 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 100 mm was shown.