Evolution of sp2 bonding with deposition temperature in tetrahedral amorphous carbon studied by Raman spectroscopy

M. Chhowalla, A. C. Ferrari, J. Robertson, G. A.J. Amaratunga

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Two transitions in the bonding are found in tetrahedral amorphous carbon (ta-C) films as a function of deposition temperature. The total sp3 fraction shows a sharp decrease at a transition temperature of order 250°C. In contrast, visible Raman finds that the sp2 sites show a gradual ordering into the graphitic clusters through the sharp bonding transition. The optical gap and resistivity show a similar, gradual transition. This indicates that the sp2 cluster size determines the optical gap, even when the sp2 content does not change. The Raman I(D)/I(G) peak ratio is found to vary inversely with the square of the gap.

Original languageEnglish
Pages (from-to)1419-1421
Number of pages3
JournalApplied Physics Letters
Issue number11
Publication statusPublished - Mar 13 2000


ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

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