DLC FILM DEPOSITION BY LASER-ARC AND STUDY OF PROPERTIES

The Laser-Arc is a controlled pulsed arc plasma source combining the advantages of the pulsed-laser deposition technique with the high energy efficiency of a vacuum arc. The potential of the laser arc method is demonstrated by preparation of high-quality amorphous carbon films (DLC) for study of their optical, electrical and mechanical properties. DLC films with a thickness of up to 500 nm were deposited on different substrate materials (Si(111) wafers, glass, steel, ZnSe, NaCl, KCl, Ge) using special preparation techniques for enhancing the substrate-film adhesion. Coating was performed in a vacuum of 10(-4) Pa from room temperature up to 500-degrees-C. The influence of deposition temperature on DLC film properties will be shown by the results of mechanical and optical studies, Elastic modulus (E) was measured by means of ultrasonic surface waves.- E values up to 230 GPa were obtained for substrate temperatures below 150-degrees-C. The very small modulus for T greater than 150-degrees-C suggests a drastic decrease of sp3/sp2 bonding ratio in the amorphous DLC structure. These results correlate with optical studies, by means of ellipsometry and the behaviour of the complex refractive index. The optical absorption at 10.6 mum ranges from 200 to 900 cm-1 and depends on the film thickness and on the substrate material. The results demonstrate that the laser arc is suitable for the preparation of DLC coatings with optical quality.