Diamond deposition on Ni/Ni-diamond coated stainless steel substrate
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Diamond deposition on NiyyNi-diamond coated stainless steel substrate A. K. Sikder, T. Sharda, and D. S. Misra Department of Physics, Indian Institute of Technology, Bombay-400 076, India
D. Chandrasekaram Department of Earth Sciences, Indian Institute of Technology, Bombay-400 076, India
P. Veluchamy and H. Minoura Department of Applied Chemistry, Gifu University, Gifu 501, Japan
P. Selvam Department of Chemistry, Indian Institute of Technology, Bombay-400 076, India (Received 26 November 1997; accepted 3 July 1998)
Electrodeposited Ni and Ni-diamond composite layers were used as diffusion barriers for Fe to facilitate the diamond growth on stainless steel substrates. Raman spectroscopy and scanning electron microscopy show the formation of good quality diamond crystallites by chemical vapor deposition. X-ray diffraction results indicate that the expansion of Ni unit cell has taken place due to the formation of the Ni–C solid solution. This observation is also well supported by x-ray photoelectron spectroscopy studies. The lattice constant of the expanded Ni unit cell matches closely with the diamond, and this may be helpful in explaining the epitaxial growth of diamond on single-crystal Ni observed by others.
I. INTRODUCTION
Close matching of the lattice constants between diamond and underlying substrate is a key parameter for growing heteroepitaxial diamond films by chemical vapor deposition (CVD). Some of the promising substrates for the heteroepitaxy of the diamond films are cubic BN, BeO, SiC, Cu, W, Mo, and Ni. Out of these, Ni has only a 4% lattice mismatch and can be an ideal candidate for the deposition of epitaxial diamond films. However, the strong catalytic effect of Ni on hydrocarbon decomposition1 and graphite formation2 at low pressure inhibits the diamond growth. In spite of this, several groups have made attempts to grow diamond epitaxially on single-crystal Ni.3 – 6 At the same time, deposition of the diamond films on stainless steel (SS) is important for the commercial applications.7–12 The direct deposition of diamond on SS substrates, however, is found to be difficult owing to the catalytic effect of Fe and large carbon solubility in it.13 Therefore, a suitable buffer layer is essential for the growth of diamond on SS. In this paper the applications of a NiyNi-diamond composite buffer layer on SS substrates, to facilitate the growth of good quality diamond on SS substrates, are reported. In the NiyNi-diamond composite buffer layer Ni acts as an effective barrier against C diffusion and the embedded diamond grains act as the nucleation centers. We expect that the CVD diamond would grow epitaxially on the embedded grains, and its deposition rate may also increase. Our results indicate that the arbitrary shaped diamond grains convert to regular cuboctahedran crystals 1148
http://journals.cambridge.org
J. Mater. Res., Vol. 14, No. 3, Mar 1999
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as a result of CVD. An expansion of the Ni unit cell is observed upon CVD due
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