Optical properties of carbon thin films containing nanoparticles

M. Chhowalla, A. I. Munindradasa, K. G. Lim, G. A.J. Amaratunga, C. J. Kiely

Research output: Contribution to journalConference articlepeer-review


The incorporation of carbon nanoparticles in the forms of nanotubes and bucky onions have shown to improve the mechanical properties of amorphous carbon (a-C) thin films. In this paper we report on the change in the optical properties of a-C films containing nanoparticles. The optical band gap, index of refraction and extinction coefficient are studied. The optical band gap in highly tetrahedral amorphous carbon (ta-C) is found to be around 2 eV. It decreases almost linearly with the sp2 fraction. It is theorized that the clustering of the sp2 sites leads to a reduction in the band gap. In this paper, we study the influence of large sp2 clusters in forms of graphitic nanoparticles on the optical of ta-C. We find that the optical gap remains around 1.8 eV even with the large inclusions of clustered nanoparticles. Furthermore, the gap remains close to 1.8 eV even when the sp2 fraction in the amorphous matrix is increased. The index of refraction however is found to decrease with the sp2 fraction indicating a reduction in density.

Original languageEnglish
Pages (from-to)115-120
Number of pages6
JournalMaterials Research Society Symposium - Proceedings
Publication statusPublished - 1997
EventProceedings of the 1997 MRS Fall Symposium - Boston, MA, USA
Duration: Dec 1 1997Dec 2 1997

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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