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E-Modul amorpher Kohlenstoffschichten

Elastic modulus of amorphous carbon films

Physica status solidi. A 145 (1994), No.385-392
ISSN: 0031-8965
ISSN: 1862-6300
Journal Article
Fraunhofer IWS ()
amorphe Kohlenstoffschicht; E-Modul; gepulste Vakuumbogenbeschichtung; Laser-Arc; Ultraschalloberflächenwelle

The elastic moduli directly reflect bonding strength and structure. Usually these factors can be only slightly modified within a given material, but in amorphous carbon films large variations of Young's modulus from less than 100 up to more than 500 GPa are found. This can be attributed mainly to the varying fraction of sp (exp 3) and sp (exp 2) bonds. Even for hard amorphous carbon films of diamond-like nature the modulus achieves only 30 to 50% of crystalline diamond. The Young's modulus is measured by a specially developed method. It is based on the determination of the frequency dependent propagation velocity of ultrasonic surface waves and its mathematical evaluation. The potential of this nondestructive method is demonstrated for amorphous carbon films down to a thickness of 100 nm. It turns out to be a suitable means for characterizing and classifying such films.