DLC FILM DEPOSITION BY LASER-ARC AND STUDY OF PROPERTIES

The Laser-Arc is a controlled pulsed arc plasma source combining the a dvantages of the pulsed-laser deposition technique with the high energ y efficiency of a vacuum arc. The potential of the laser arc method is demonstrated by preparation of high-quality amorphous carbon films (D LC) 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, G e) using special preparation techniques for enhancing the substrate-fi lm adhesion. Coating was performed in a vacuum of 10(-4) Pa from room temperature up to 500-degrees-C. The influence of deposition temperatu re on DLC film properties will be shown by the results of mechanical a nd optical studies, Elastic modulus (E) was measured by means of ultra sonic surface waves.- E values up to 230 GPa were obtained for substra te temperatures below 150-degrees-C. The very small modulus for T grea ter than 150-degrees-C suggests a drastic decrease of sp3/sp2 bonding ratio in the amorphous DLC structure. These results correlate with opt ical studies, by means of ellipsometry and the behaviour of the comple x 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 ma terial. The results demonstrate that the laser arc is suitable for the preparation of DLC coatings with optical quality.