For many industrial applications such as cutting tools, optical components
and microelectronic devices the control of film structure and morphology is
of critical importance. The crystallite size, orientation, surface roughne
ss and the degree of sp(3) character have a profound effect on the mechanic
al, electrical and optical properties of the films deposited. In this paper
we present new results on the effects of substrate pre-treatment, biasing
and nitrogen doping on the growth rate, orientation, crystallite size, surf
ace roughness and film resistivity. Preliminary results on the effects of p
ulsed biasing of the substrate on the film morphology are reported. It has
been shown that as the particle size of the polishing material, for both di
amond powder and alumina powder, is reduced the nucleation density is enhan
ced due to the creation of a greater number of nucleation sites. Diamond is
harder than alumina and therefore creates more nucleation sites giving a h
igher deposition rate than alumina. Increasing the bias voltage can signifi
cantly alter the crystallite size, surface roughness and texture of the fil
ms deposited. For nitrogen doping it has been shown that the growth rate, r
esistance and the degree of sp3 character optimises at 200 ppm of nitrogen
and all these properties degrade considerably with increasing nitrogen conc
entration. This has been related to carbon supersaturation of the surface.
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