The interface between the silicon substrate and a carbon nanotube film grown by thermal CVD with acetylene (C2H2) and hydrogen at 750 or 900 °C has been characterized by high resolution and analytical transmission electron microscopy, including electron spectroscopic imaging. Silicon (002) substrates coated with a thin (2.8 nm) iron film were heat treated in the CVD furnace at the deposition temperature in a mixture of flowing argon and hydrogen whereby nanosized particles of (Fe,Si)3O4 formed. These particles were reduced to catalytic iron silicides with the α-(Fe, Si), α2-Fe2Si and α1-Fe2Si structures during CVD at 900 °C, and multi-wall carbon nanotubes grew from supported particles via a base-growth mechanism. A limited number of intermediate iron carbides, hexagonal and orthorhombic Fe7C3, were also present on the substrate surface after CVD at 900 °C. The reduction of the preformed (Fe, Si}3O4 particles during thermal CVD at 750 °C was accompanied by disintegration leading to the formation of a number of smaller ( < 5 and up to 10 nm iron and silicon containing particles. It is believed that the formation of these small particles is a prerequisite for the growth of aligned multi-wall carbon nanotube films.
|Number of pages||11|
|Journal||Journal of Materials Science: Materials in Electronics|
|State||Published - Aug 2004|
Bibliographical noteFunding Information:
Financial support from the Swedish Foundation for Strategic Research is gratefully acknowledged.