Substrate Position Influence in the DC Plasma Jet Chemical Vapour Deposition of Diamond

 

Miroljub Vilotijević

Marija Krmar

 

The influence of the substrate position in the different regions of the plasma jet was examined depending on the morphology, deposition rate, surface area of the deposited diamond films and their phase purity while other parameters of the process were kept constant (CH₄/H₂ ratio, plasma power, chamber pressure and substrate temperature). An increase in the substrate distance from the anode nozzle opening of the torch leads to a considerable change in morphology (from a perfect crystallinity to a ball-like structure), as well as to a decrease in deposition rate and an increase in the coated surface area. According to XRD findings, the phase purity of the deposits does not deteriorate significantly, so it can be described as a diamond coating in the entire region studied. A reason could be the enthalpy of plasma gases high enough to preserve a relatively high concentration of atomic hydrogen which is known as a good etchant for non-diamond carbon phases.

Key words: diamond, chemical vapour deposition, plasma jet.