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Influence of nitrogen on the structure and nanomechanical properties of pulsed laser deposited tetrahedral amorphous carbon

Biomedical Sciences Research Institute Computer Science Research Institute Environmental Sciences Research Institute Nanotechnology & Advanced Materials Research Institute

Papakonstantinou, P and Lemoine, P (2001) Influence of nitrogen on the structure and nanomechanical properties of pulsed laser deposited tetrahedral amorphous carbon. JOURNAL OF PHYSICS-CONDENSED MATTER , 13 . pp. 2971-2987. [Journal article]


URL: http://iopscience.iop.org/0953-8984/13/13/311/

DOI: 10.1088/0953-8984/13/13/311


The effect of nitrogen addition on the structure and nanomechanical properties of tetrahedral amorphous carbon, t alpha -C, has been studied. The t alpha -C films were grown on Al2O3-TiC substrates by reactive pulsed KrF excimer laser ablation of graphite targets at a laser fluence of 10 J cm(-2). Nitrogen contents up to 19 at.% were obtained by increasing the nitrogen partial pressure, P-N2 to 75 mTorr. The sp(3) content in the t alpha -C film as determined by analysis of the XPS C Is core level spectra had a value of about 76%. Incorporation of a small amount of nitrogen, 2 at.%, reduces the clustering of the sp(2) phase and improves the nanomechanical properties of the t alpha -C films, whilst for higher nitrogen concentrations the carbon bonding changes progressively from sp(3) to sp(2). Quantitative analysis of the Raman spectra indicated that incorporation of nitrogen greater than 2 at.% induced a progressive long-range order in the amorphous carbon and an increase in the size Of sp(2) graphitic clusters. Additionally, Raman spectroscopy established the presence of C equivalent toN bonds at high P-N2. To elucidate the influence of the substrate on the measurement of the nanomechanical properties of thin film a continuous measure of hardness and modulus as a function of depth was performed. Both the hardness and Young's modulus were significantly reduced from 56 and 573 GPa for CN0.02 to 2 and 44 GPa for CN0.19 at a contact depth of 25 nm. The deterioration of the nanomechanical properties with N incorporation is consistent with the spectroscopic results, which indicate a structural transformation from an amorphous structure consisting predominately of spl C bonds to an spl graphitic-like phase.

Item Type:Journal article
Faculties and Schools:Faculty of Computing & Engineering
Faculty of Computing & Engineering > School of Engineering
Research Institutes and Groups:Engineering Research Institute
Engineering Research Institute > Nanotechnology & Integrated BioEngineering Centre (NIBEC)
ID Code:14402
Deposited By:Professor Pagona Papakonstantinou
Deposited On:01 Jul 2010 09:42
Last Modified:18 Aug 2011 11:48

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