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Diamond-like carbon: state of the art

A general framework for the interpretation of infrared and Raman spectra of amorphous carbon nitrides is presented. In the first part of this paper we examine the infrared spectra. The peaks around 1350 and 1550 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ found in the infrared spectrum of amorphous carbon nitride or hydrogenated and hydrogen-free amorphous carbon are shown to originate from the large dynamic charge of the more delocalized \ensuremath{\pi} bonding which occurs in more ${\mathrm{sp}}^{2}$ bonded networks. The IR absorption decreases strongly when the \ensuremath{\pi} bonding becomes localized, as in tetrahedral amorphous carbon. Isotopic substitution is used to assign the modes to $\mathrm{C}=\mathrm{C}$ skeleton modes, even those modes around 1600 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ which become strongly enhanced by the presence of hydrogen. The infrared spectrum of carbon nitride may resemble the Raman spectrum at some excitation energy, but the infrared activity does not primarily result from nitrogen breaking the symmetry. In the second part we examine the Raman spectra. A general model is presented for the interpretation of the Raman spectra of amorphous carbon nitrides measured at any excitation energy. The Raman spectra can be explained in terms of an amorphous carbon based model, without need of extra peaks due to CN, NN, or NH modes. We classify amorphous carbon nitride films in four classes, according to the corresponding N-free film: $a\ensuremath{-}\mathrm{C}:\mathrm{N},$ $a\ensuremath{-}\mathrm{C}:\mathrm{H}:\mathrm{N},$ $ta\ensuremath{-}\mathrm{C}:\mathrm{H}:\mathrm{N},$ and $ta\ensuremath{-}\mathrm{C}:\mathrm{N}.$ We analyze a wide variety of samples for the four classes and present the Raman spectra as a function of N content, ${\mathrm{sp}}^{3}$ content, and band gap. In all cases, a multiwavelength Raman study allows a direct correlation of the Raman parameters with the N content, which is not generally possible for single wavelength excitation. The G peak dispersion emerges as a most informative parameter for Raman analysis. UV Raman enhances the ${\mathrm{sp}}^{1}$ CN peak, which is usually too faint to be seen in visible excitation. As for N-free samples, UV Raman also enhances the C-C ${\mathrm{sp}}^{3}$ bonds vibrations, allowing the ${\mathrm{sp}}^{3}$ content to be quantified.

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Interpretation of infrared and Raman spectra of amorphous carbon nitrides

Carbon doped oxide dielectrics comprised of Si, C, O, and H (SiCOH) have been prepared by plasma enhanced chemical vapor deposition (PECVD) from mixtures of tetramethylcyclotetrasiloxane (TMCTS) and an organic precursor. The films have been analyzed by determining their elemental composition and by Fourier transform infrared spectroscopy with deconvolution of the absorption peaks. The analysis has shown that PECVD of TMCTS produces a highly crosslinked networked SiCOH film. Dissociation of TMCTS appears to dominate the deposition chemistry as evidenced by the multitude of bonding environments and formation of linear chains and branches. Extensive crosslinking of TMCTS rings occurs through Si–Si, Si–CH2–Si, Si–O–Si, and Si–CH2–O–Si moieties. The films deposited from mixtures of TMCTS and organic precursor incorporate hydrocarbon fragments into the films. This incorporation occurs most probably through the reaction of the organic precursor and the Si–H bonds of TMCTS. Annealing the SiCOH films deposited fro...

Structure of low dielectric constant to extreme low dielectric constant SiCOH films: Fourier transform infrared spectroscopy characterization

Significance of calcium phosphate coatings for the enhancement of new bone osteogenesis – A review ☆

Mechanisms of plasma polymerization of various silico-organic monomers

Recent results in cubic boron nitride deposition in light of the sputter model

Structural investigation of nanocrystalline diamond/amorphous carbon composite films

Growth and characterization of nanocrystalline diamond/amorphous carbon composite films prepared by MWCVD

Nanocrystalline diamond/amorphous carbon (NCD/a-C) composite films have been deposited by microwave chemical vapour deposition from methane-rich CH4/N2 mixtures and characterized carefully by a variety of methods with respect to morphology and structure, composition, crystallinity, and bonding environment. The films consist of diamond nanocrystals of 3–5 nm diameter, which are embedded in an amorphous carbon matrix of 1–1.5 nm width. The matrix is a mixture of sp2 (20–30%) and sp3 bonded carbon and contains about 20% of hydrogen, mostly bonded to sp3 carbon atoms. New experiments are reported carried out to study the nucleation and the growth on a microscopic and macroscopic scale. No differences to standard deposition of polycrystalline diamond (PCD) with respect to the nucleation step were observed, i.e. in order to achieve a high nucleation density an appropriate substrate pretreatment is required. In contrast, there are strong differences in the growth mechanisms of NCD and PCD, respectively. Most importantly, there is a high rate of secondary nucleation observed in NCD deposition. On a macroscopic scale, this leads to a spherulitic growth of NCD films. The microscopic mechanisms leading to this high rate of secondary nucleation are discussed in terms of the deposition parameters leading to NCD growth, namely gas phase constituents and composition, pressure, substrate temperature, and bias voltage. Defect formation under the special conditions of NCD deposition is identified as a major reason. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Wilhelm Kulisch

Papers

Mechanisms of plasma polymerization of various silico-organic monomers

Recent results in cubic boron nitride deposition in light of the sputter model

Structural investigation of nanocrystalline diamond/amorphous carbon composite films

Growth and characterization of nanocrystalline diamond/amorphous carbon composite films prepared by MWCVD

On the growth mechanisms of nanocrystalline diamond films