Dynamic relaxation of the elastic properties of hard carbon films

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Journal Title
Journal ISSN
Volume Title
School of Science | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
1997
Major/Subject
Mcode
Degree programme
Language
en
Pages
7248-7254
Series
Journal of Applied Physics, Volume 81, Issue 11
Abstract
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.
Description
Keywords
carbon films, tight-binding methods, elasticity, thin films
Other note
Citation
Hirvonen, J.-P. & Koskinen, J. & Kaukonen, M. & Nieminen, Risto M. & Scheibe, H.-J. 1997. Dynamic relaxation of the elastic properties of hard carbon films. Journal of Applied Physics. Volume 81, Issue 11. 7248-7254. ISSN 0021-8979 (printed). DOI: 10.1063/1.365322.