GROWTH METHODOLOGIES AND CHARACTERIZATION OF DIFFERENT POLYCRYSTALLINE DIAMOND FILMS ON TA SUBSTRATES

The results of research undertaken with the aim of setting up a proced ure for coating tantalum plates with good quality diamond films are pr esented. The deposition was carried out using a hot filament chemical vapour deposition technique from mixtures of methane and hydrogen. The morphology of the deposits was characterized by scanning electron mic roscopy and replica transmission electron microscopy, while the struct ural properties were analysed by reflection high energy electron diffr action. The effects of modification of the substrate surface on both t he nucleation density and growth rates of diamond crystallites were in vestigated. Deposition experiments were carried out using ''as receive d'' and variously treated Ta substrates. A suitable choice of experime ntal conditions allowed us to obtain fine grained and oriented polycry stalline diamond coatings. Good adhesion to the substrate can be achie ved by employing a particular procedure at the end of the deposition p rocess.