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.