Production of Diamond Films at High Rates using a DC Arc Jet
Between 1997 and 2007 we studied the growth of CVD diamond using a 10 kW DC Arc Jet system which was on loan from Element Six. The project was sponsored by the EPSRC and its aims were to:
- grow diamond at high rates (hopefully 100 μm h-1 or more)
- understand the chemistry occurring in this hostile environment using sophisticated laser probing techniques.
We stopped working on the DC arcjet in early 2007 to concentrate on MW CVD diamond.
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| The DC Arc Jet system | Close up of the Arc Jet chamber and pumps |
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| The torch plume striking the substrate | Cross-section of a 100 μm-thick CVD diamond film grown by DC arc jet. The columnar nature of the growth is clearly evident, as is the increase in film quality and grain size with growth time. |
The torch could, indeed, deposit CVD diamond a very fast rates (100 μm/h), but only on molybdenum substrates, as other substrates, such as Si, simply shattered when the torch was turned on or off due to the rapid thermal shock. The growth area was confined to a small region around 5 mm in diameter, and the growth rate was high but not very uniform over this area. The main problem was the cooling - removing 10 kW of heat required pumping a large quantity of cold water around the system at high pressure - and this frequently led to burst pipes, water leaks and even floods!
Although this system was not really practical as a route to growing diamond films reliably, it was important in our early studies of diamond growth mechanisms as the bright torch plume was relatively easy to study via optical emission spectroscopy and other laser probing techniques. A such, we gained a lot of important insights into the gas-phase chemistry operating within the hostile CVD growth environment, which later fed into our models for diamond growth, and ultimately our kMC models of the overall growth process.
Related Papers
- J.A. Smith, K.N. Rosser, H. Yagi, M.I. Wallace, P.W. May and M.N.R. Ashfold, "Diamond deposition in a DC-arc Jet CVD system: Investigations of the effects of nitrogen addition" Diamond Relat. Mater., 10 (2001) 370-375.
- Yu.A. Mankelevich, N.V. Suetin, M.N.R. Ashfold, W.E. Boxford, A.J. Orr-Ewing, J.A. Smith and J.B. Wills, "Chemical kinetics in carbon depositing d.c.-arc jet CVD reactors", Diamond Relat. Mater. 12 (2003) 383-90.
- J.B. Wills, M.N.R. Ashfold, A.J. Orr-Ewing, Y.A. Mankelevich and N.V. Suetin, "Number density and temperature of acetylene in hot-filament and arc-jet activated CH4/H2 gas mixtures measured using diode laser cavity ring-down absorption spectroscopy", Diamond Relat. Mater. 12 (2003) 1346-1356.
- C.J. Rennick , A.G. Smith, J.A. Smith , J.B. Wills, A.J. Orr-Ewing , M.N.R. Ashfold, Yu.A. Mankelevich, N.V. Suetin, "Improved characterisation of C2 and CH radical number density distributions in a DC arc jet used for diamond chemical vapour deposition", Diamond Relat. Mater., 13 (2004) 561-8.
- C.J. Rennick, R. Engeln, J.A. Smith, A.J. Orr-Ewing, M.N.R. Ashfold, Yu.A. Mankelevich, "Measurement and modeling of a diamond deposition reactor: Hydrogen atom and electron number densities in an Ar/H2 arc jet discharge", J. Appl. Phys. 97 (2005) 113306-113315.
- Yu. A. Mankelevich, M.N.R. Ashfold and A.J. Orr-Ewing, "Measurement and modeling of Ar/H2/CH4 arc jet discharge chemical vapor deposition reactors. II. Modeling of the spatial dependence of expanded plasma parameters and species number densities", J. Appl. Phys. 102 (2007) 063310 1-11.