Dynamic relaxation of the elastic properties of hard carbon films

Juha-Pekka Hirvonen, Jari Koskinen, Markus Kaukonen, Risto Nieminen, Hans-Joachim Scheibe

Research output: Contribution to journalArticleScientificpeer-review

28 Citations (Scopus)


The effect of enhanced atomic mobility on the growth of hard carbon films was examined. Tetrahedrally bonded amorphous carbon films were deposited by condensing energetic carbon ions using an arc-discharge deposition method. The deposition temperature varied between 50 and 400 °C. The dependence of elastic properties on deposition temperature was examined by determining the frequency-dependent propagation velocity of ultrasonic surface acoustic waves induced by a laser. A remarkable decrease in elastic coefficient was revealed above the deposition temperature of 300 °C and complete relaxation was obtained at 400 °C. This observation was analyzed by using a simple model which was in turn supported by molecular dynamics simulations. The relaxation turns out to be a thermally activated, dynamic process with an activation energy of 0.57 eV. Possible relaxation mechanisms associated with the migration of atoms or defects on a growing surface are discussed.
Original languageEnglish
Pages (from-to)7248-7254
JournalJournal of Applied Physics
Issue number11
Publication statusPublished - 1997
MoE publication typeA1 Journal article-refereed


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