DAMAGE AND STRUCTURAL MODIFICATION OF CVD DIAMOND FILMS CAUSED BY ALPHA-PARTICLES

Polycrystalline diamond films grown in a microwave (MW) plasma reactor onto Si(100) substrates were exposed to 2 MeV He-4(+)-particles in th e range of fluences of 10(17)-10(18) cm(-2). The formation of a crater , the depth of which varies with the ion dose, was observed. Raman spe ctroscopy shows that the diamond in the center of the crater was compl etely transformed into DLC amorphous structure, At the crater edges, t he structure of the crystalline facets was not much affected but the c hemical structure of C-C bonds was strongly modified. The nature of de fects and modifications to the C-C bonds caused by the ct-particles ar e compared to damage due to carbon atom implantation. Hot filament (HF ) CVD diamond films were also exposed to high He-4(+) ions fluence. No crater formation was observed but strong C-C bond modification occurs , leaving the material in a state similar to that of the crater edges in MW CVD films.