Damage and structural modification of CVD diamond films caused by α-particles

Abstract Polycrystalline diamond films grown in a microwave (MW) plasma reactor onto Si(100) substrates were exposed to 2 MeV 4 He + -particles in the 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 spectroscopy shows that the diamond in the center of the crater was completely transformed into DLC amorphous structure. At the crater edges, the structure of the crystalline facets was not much affected but the chemical structure of CC bonds was strongly modified. The nature of defects and modifications to the CC bonds caused by the α-particles are compared to damage due to carbon atom implantation. Hot filament (HF) CVD diamond films were also exposed to high 4 He + 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.