Structural modifications of diamond films induced by pulsed laser treatment

Diamond thin films promise excellent performances in several high value applications such as high temperature and high frequency electronic devices, as electrode material in electrochemistry, and as a protective coating for components operating in aggressive environments. These interesting perspectives, however, are actually limited by the polycrystalline, randomly oriented morphology of CVD deposited films, which results in a noticeable surface roughness with some presence of pin holes. Many methods have been thed to polish diamond, the hardest known material; a very simple and effective one seems to be the irradiation with hizh energy pulsed lasers. The purpose of this work is to get a deeper insight into the interactions and effects of intense laser radiation on diamond, a wide band gap material, and to explore the optimal experimental conditions to smooth the surface roughness and eventually to fill in the pin-holes. HF-CVD deposited diaimnd films have been treated by radiations of energy values larger (ArF, A = 193 nm, hv 6.4 eV) and smaller (Nd:YAG, X = 532 nm, liv 2.3 eV) than the electronic energy gap (hv 5.4 eV). The surface morphology modifications have been studied by SEM. Raman spectroscopy was employed to evaluate some phase transition in the C component (diamond--> DLC--> graphite--> amorphous C).