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A study of ta-C, a-C : H and Si-a : C : H thin films on polymer substrates as a gas barrier

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

Abbas, GA, McLaughlin, JAD and Harkin-Jones, E (2004) A study of ta-C, a-C : H and Si-a : C : H thin films on polymer substrates as a gas barrier. DIAMOND AND RELATED MATERIALS, 13 (4-8). pp. 1342-1345. [Journal article]

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URL: http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6TWV-4B9DB3W-C-8&_cdi=5572&_user=126978&_orig=search&_coverDate=08%2F31%2F2004&_sk=999869995&view=c&wchp=dGLbVzz-zSkzk&md5=a76726ea60bd6ce0bedf514a860c0094&ie=/sdarticle.pdf

DOI: 10.1016/j.diamond.2003.10.084

Abstract

Two types of diamond-like carbon (DLC) films were grown on Poly (ethylene terepthalate) (PET) substrates have been investigated for density, internal stress, gas permeability and structural properties by an X-ray reflectometry, surface profilometer, Raman spectroscopy and water vapour permeation analysis system, respectively. The high density tetrahedral amorphous carbon (ta-C) films (3.27 g/cm(3)) prepared by filtered vacuum cathodic arc (FCVA) showed unexpected high water vapour transmission rate (WVTR) (1.3 g/m(2) day) and a surface covered by a network of deep micro-cracks, which is due to intrinsic stress inside the ta-C films (up to 12 GPa). The soft Si doped hydrogenated amorphous carbon (Si-a:C:H) films prepared by plasma enhanced chemical vapour deposition (PECVD) exhibited low transmission rate (0.03 g/m(2) day) with a water vapour reduction factor up to 98% and a surface almost completely free of micro-cracks. Si incorporation in the a-C:H films reduced both the film density from 2.3 g/cm(3) to 1.85 g/cm(3) and the compressive stress to < 0.5 GPa. This could be understood by two possibilities. Firstly, the increasing in the hydrogen content within the films (as indicated by increasing the Raman background slope) developed more polymer-like bonds, which weakens the microstructure. Second, replacing the stronger C-C bonds (3.7 eV) by C-Si (3.21 eV) bonds where the relaxation of residual stress would occur with large strains in the C-Si bonds. (C) 2003 Elsevier B.V. All rights reserved.

Item Type:Journal article
Keywords:DLC; coatings; diffusion; surface characterization
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:298
Deposited By:Mrs Ann Blair
Deposited On:17 Sep 2009 15:02
Last Modified:15 Jun 2011 10:51

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