DIAMOND DEPOSITION BY HOLLOW-CATHODE ARC-DISCHARGE

We have studied the influence of various discharge and deposition para meters on the operation of an HCA discharge as well as on the formatio n of polycrystalline diamond films, using this rarely investigated CVD method. Obvious changes and dependencies of the growth of diamond par ticles and films were observed with variation of the distance between hollow cathode tip and substrate, deposition temperature, working pres sure, methane concentration in hydrogen, total gas flow and deposition time. With our improved HCA discharge system, which can be used for d eposition with mainly thermal, mainly kinetic or combined activation o f the gas mixture, diamond films have been obtained with a growth rate up to 3 mum h-1. From the various methods of investigation we can con clude that the electron current to the substrate, a characteristic fea ture of the HCA discharge method, is actually a main influence factor for plasma-activated deposition of diamond and not only for substrate heating. Increasing the substrate current results in higher growth rat es, improved film uniformity and changed surface morphologies of the d iamond deposits.