Published in: High Pressure Research, Volume 28, Issue 1 March 2008 ,
pages 1 - 8
Growth chemistry for the fabrication of designer diamonds for high
pressure research
Authors: Gopi Samudrala a; Wei Qiu a; Shane A. Catledge a; Joseph
G. Harrison a; Yogesh K. Vohra a; Samuel T. Weir b
Affiliations: a Department of Physics, University of Alabama at
Birmingham (UAB), Birmingham, AL, USA
b Lawrence Livermore National Laboratory, Livermore, CA, USA
We report our observations on the catalytic effect of nitrogen in the
growth of diamond on top of a diamond anvil substrate by microwave
plasma chemical vapor deposition technique. The diamond deposition
experiments were carried out by varying the nitrogen content in the
range 0-3500 ppm in a standard hydrogen/methane/oxygen plasma. We
employ isotopically enriched C-13 methane gas as the source of carbon
in the plasma to clearly distinguish the grown diamond layer from the
underlying substrate using Raman spectroscopy. The measured diamond
growth rate shows a sharp peak at a nitrogen content of 1000 ppm in
our growth experiments carried out at 1212=B0C and atomic force
microscopy reveals a dramatic change in surface morphology.
Thermodynamic calculations of the plasma show that this growth
enhancement could be the result of a competition between the CN and
CH3 radicals in the plasma. Finally, we show an application of this
'unique chemistry' by synthesizing several designer diamonds with
embedded sensors for high-pressure materials research experiments.
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