Thermal stability and relaxation in diamond-like-carbon. A Raman study of films with different sp3 fractions (ta-C to a-C)

Abstract

The thermal stability and relaxation processes in hydrogen free diamond-like-carbon films with different sp3 fractions (40%, 60%, and 80%) are comparatively studied for the first time by visible Raman spectroscopy. The 80% sp3 film is very stable under annealing in the entire temperature region investigated (300-1270 K) and shows only a minor change of the optical transmission, most likely due to a mild sp2 clustering, but no graphitization. This is very important for practical applications requiring a high thermal stability. The films with lower sp3 fraction show a thermal stability which decreases with the decreasing sp3. Graphitization starts at 700 K for the 40% sp3 film. © 1999 American..