Laser treatment of diamond films

Diamond thin films promise excellent performance in several application fields such as high-temperature and highfrequency electronics, protective coatings for components exposed to aggressive ambient conditions, and electrode materials in electrochemistry. However, these interesting perspectives are presently limited by the polycrystalline morphology of deposited films that include a noticeable surface roughness and the presence of pinholes. The objectives of this work are to get a deeper understanding of the interactions and effects of intense radiation on wide band gap materials, and to explore the conditions that may better smooth the surface roughness and fill the pinholes. A comparison is made between the effects induced on HF-CVD deposited diamond films by radiation of energy values larger ArF, ls193 nm, hn(6.4 eV.and smaller Nd:YAG, ls532 nm, hn(2.3 eV.than the electronic energy gap hn(5.4 eV.. These are analyzed by SEM and Raman spectroscopy. The radiation of the Nd:YAG laser leaves the diamond thin film largely unaffected and is highly absorbed by the silicon substrate. The ArF laser radiation, on the other hand, shows a much larger absorption, probably associated with an electronic transition from the valence band to the vacuum, which cannot be performed at first order by electronic transitions induced by Nd:YAG radiation. q1998 Elsevier Science B.V.