Dynamic relaxation of the elastic properties of hard carbon films

J. P. Hirvonen*, J. Koskinen, Markus Kaukonen, R. Nieminen, H. J. Scheibe

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

28 Citations (Scopus)
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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
Number of pages7
JournalJournal of Applied Physics
Issue number11
Publication statusPublished - 1997
MoE publication typeA1 Journal article-refereed


  • carbon films
  • tight-binding method


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