Investigation of the initial growth of ultrananocrystalline diamond films by multiwavelength Raman spectroscopy

W. Kulisch, C. Popov, H. Rauscher, M. Rinke, M. Veres

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

The initial growth phase of ultrananocrystalline diamond/amorphous carbon nanocomposite films (UNCD/a-C) has been investigated by scanning electron microscopy, atomic force microscopy and especially Raman spectroscopy. As due to resonance effects Raman spectra of carbon materials strongly depend on the excitation wavelength, a multiwavelength analysis has been performed with λexc ranging from the UV region (325 nm) over the visible range (488 and 514 nm) to the IR region (785 nm). In addition, a set of measurements has been performed with a confocal Raman microscope, i.e. depth resolved, with a wavelength of 532 nm. The samples investigated were deposited with constant parameters, the deposition time being the only parameter varied, resulting in film thicknesses from 100 to 500 nm. It turned out that the diamond fraction and also the grain boundary material do not vary during that stage whereas there are slight but distinct changes of the nature of the amorphous matrix which reflect, among others, in a shift of the graphite-related G band to higher wavenumbers and in an increase of the ratio of D and G bands with increasing film thickness. These changes are discussed in terms of the above mentioned resonance effects; the major changes are a transition of hydrogen containing sp2 chains to hydrogen-free condensed sp2 rings when the material is no longer in the surface region of the films but becomes incorporated within the film bulk.

Original languageEnglish
Pages (from-to)1076-1080
Number of pages5
JournalDiamond and Related Materials
Volume20
Issue number7
DOIs
Publication statusPublished - Jul 1 2011

Keywords

  • Growth mechanisms
  • Nucleation mechanisms
  • Raman spectroscopy
  • Ultrananocrystalline diamond

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Chemistry(all)
  • Mechanical Engineering
  • Materials Chemistry
  • Electrical and Electronic Engineering

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