CARBON DEPOSITION USING AN EXPANDING CASCADED ARC DC PLASMA

In this work a strongly flowing cascaded arc burning on an argon-hydrogen mixture is used to dissociate and ionize hydrocarbons which are injected inside a nozzle which is mounted in the anode of the arc. The thermal plasma (T almost-equal-to 10 000 K, p almost-equal-to 0.5 bar) will then expand supersonically into a vessel where the pressure can be varied between 0.1 mbar and 100 mbar. In the expansion the cracked hydrocarbons are transported towards a substrate opposing the arc where carbon films can grow. The large number of more or less independent operational variables make it possible to grow any kind of carbon film from graphite to diamond to polymers and amorphous hydrogenated carbon (a-C:H). For the amorphous films growth rates up to 200 nm s-1 on an area of 100 cm2 were achieved, while for polycrystalline diamond films the rate was 25-mu-m h-1, on areas of about 3 cm2. Graphite has been grown on top of graphite and steel samples at rates up to 3 mm h-1. The morphology and film parameters of the grown films were investigated with ellipsometry (a-C:H, refractive index etc.), Raman spectroscopy (diamond, graphite, crystallinity and bond structure), electron microscopy (morphology).