Plasma Materials: Synthesis and Modification

Prof John I B Wilson

A diverse set of thin-film materials has been synthesised or surface-modified by electrical plasma processing. From our early development of amorphous silicon solar cells to our latest nanocrystalline diamond coatings, we have used a combination of gas mixtures and high frequency plasma sources to solve problems in materials applications. These have frequently involved a temperature limitation set by the nature of the substrate, such as low cost glass or polymers. Plasma deposition, using either RF or microwave excitation, overcomes the restriction of low substrate temperatures that would otherwise impair the quality of the coating. Our publications describe the low pressure RF plasma deposition of amorphous silicon, silicon nitride and silicon carbide, for optical and electronic applications. In collaboration with Prof P John, Chemistry, other papers describe how higher pressures and microwave plasmas are producing polycrystalline or epitaxial diamond for mechanical or biomedical applications. EPSRC are currently funding a £1.4M project to investigate diamond coatings for plasma-facing components in tokamak fusion reactors, in collaboration with materials modellers at UCL, UKAEA Culham, and two manufacturers of carbon tiles. Previously, improved design of plasma deposition equipment was driven through the establishment of a company, DILAB Limited, and its success in gaining SMART funding. One further outcome is the present development of microwave plasma deposited nanocrystalline silicon for flexible solar cells on textiles: this is supported by a Scottish Government SMART grant to a newcompany, Power Textiles Limited (co-directors RR Mather & JIB Wilson). Plasma deposition has produced thin polymer coatings to enhance the performance of steam condensers used by the electricity generating industry, and plasmas may also change the surface properties of materials, for instance making PTFE hydrophilic for medical components. New projects, that continue to combine the expertise of chemists and physicists in utilising plasma enhanced chemical vapour deposition, are concerned with both nano- and macro-sized substrates, and involve a range of spectroscopic techniques to probe the process and the products.


Recent Publications

R.R. Mather, J.I.B. Wilson “Solar textiles: production and distribution of electricity coming from solar radiation and applications” Intelligent Textiles and Clothing, ed H. Mattila, Woodhead Publishing (Cambridge) 2006, chapter 12. E. Ekevall, J.I.B. Wilson, R.R. Mather “The effect of ammonia and sulphur dioxide gas plasma treatments on polymer surfaces” Medical Textiles and Biomaterials for Healthcare, ed S.C. Anand, M. Miraftab, S. Rajendran, J.F. Kennedy, Woodhead Publishing (Cambridge) 2006, p 491-498 (ISBN 1 85573 683 7) J.I.B. Wilson “Amorphous semiconductors” Encyclopaedia of Modern Optics, ed R.D. Guenther, D.G. Steel, L. Bayvel, Elsevier Ltd (Oxford), 2005, 6 pp. (ISBN D-12-227600-0) S. Jardine & J.I.B. Wilson “Plasma surface modification of ePTFE vascular grafts” Plasma Process. Polym. 2, 328-333, 2005. JR Rabeau, P John, JIB Wilson, Y. Fan “The role of C2 in nanocrystalline diamond growth”. J Appl Phys 96, 6724-6732, 2004. D.V. Isakov, V.I. Petrov, M.V. Chukichev, P. John, N. Polwarth, J. Wilson, Y.Y. Liu, D.S.H. Chan, J.C.H. Phang “Cathodoluminescnce of diamond films grown by microwave plasma chemical deposition” 3rd International Conference on Advanced Materials Processing (ICAMP-3), Melbourne, Non-Dec 2004. I.S. Forbes, J.R. Rabeau, J.I.B. Wilson, P. John “Nanocrystalline diamond films for nanotechnology applications” Materials Science and Technology 19, 553-556, 2003. A.F. Richardson, A. Neville, J.I.B. Wilson “Investigating feasibility of incorporating diamond into metal matrix composites using thermal spraying” Surface Engineering 19, 114-120, 2003. [P. John, N. Polwart, C.E. Troupe, J.I.B. Wilson “The oxidation of diamond: the geometry and stretching frequency of carbonyl on the (100) surface” J. Am. Chem. Soc. 125, 6600-6601, 2003. Richardson AF, Neville A, Wilson JIB “Developing diamond MMCs to improve durability in aggressive abrasive conditions” Wear 255 Part 1, 593-605, 2003. Y. Fan, A.G. Fitzgerald, P. John, C.E. Troupe, J.I.B. Wilson “X-ray photoelectron spectroscopy studies of CVD diamond films” Surf. Interface Anal. 34, 703-7, 2002. I.S. Forbes, J.I.B. Wilson “Diamond and hard carbon films for microelectromechanical systems (MEMS) – a tribological study” Thin Solid Films 420/421, 508-514, 2002. K. Chakrabarti, J.B. Kim, J.I.B. Wilson, C. Lee “Effects of Ar gas dilution in methane plasma on the properties of diamond-like carbon films” phys. stat. sol. 194, 112-117, 2002. P. John, J.R. Rabeau, J.I.B. Wilson “The cavity ring-down spectroscopy of C2 in a microwave plasma” Diamond & Related Materials 11, 608-611, 2002. P. John, N. Polwart, C.E. Troupe, J.I.B. Wilson “The oxidation of (100) textured diamond” Diamond & Related Materials 11, 861-866, 2002. J.I.B. Wilson, N. Scheerbaum, S. Karim, N. Polwart, P. John, Y. Fan, A.G. Fitzgerald “Low temperature plasma chemical vapour deposition of carbon nanotubes” Diamond & Related Materials 11, 918-921, 2002. J.I.B. Wilson, J.S. Walton, G. Beamson, "Analysis of CVD Diamond Films by XPS" J Electron Spectroscopy & Related Phenomena, 121, 183-201, 2001. A.G. Fitzgerald, Y. Fan, C. Kisielowski, P. John, C.E. Troupe, J.I.B. Wilson “High resolution TEM observation of CVD diamond films” Inst. Phys. Conf. Ser. No. 168, section 2, EMAG2001, Dundee, 2001 pp. 39-42. A.G.Fitzgerald, Y.Fan, P.John, C.E.Troupe, J.I.B.Wilson, A.O.Tooke, B.E.Storey, "Study of the interface microstructures of CVD diamond films by TEM" Mikrochim. Acta, 132, 315-321, 2000. Y.Fan, A.G.Fitzgerald, P.John, C.E.Troupe, J.I.B.Wilson, "Scanning probe microscopy and spectroscopy of CVD diamond films" Mikrochim. Acta, 132, 435-441, 2000. Y.Fan, A.G.Fitzgerald, J.A.Cairns, P.John, C.E.Troupe, J.I.B.Wilson, "A novel STM-based depth profiling technique for the electronic characterisation of thin film materials" Appl. Surf. Sci., 162-163, 630-637, 2000. A.G.Fitzgerald, Y.Fan, P.John, C.E.Troupe, J.I.B.Wilson, "Characterization of the surface morphology and electronic properties of microwave enhanced chemical vapor deposited diamond films" J.Vac.Sci.Technol. B, 18, 2714, 2000. A.G.Fitzgerald, Y.Fan, P.John, C.E.Troupe, J.I.B.Wilson, "Microstructural studies of CVD diamond films by transmission electron microscopy" Presented at EMAG99, Sheffield 1999; Inst Phys. Conf. Ser. No. 161, section 8, p.413-416, 1999.