Epitaxial growth of multiwall carbon nanotube from stainless steel substrate and effect on electrical conduction and field emission.

The epitaxial growth of carbon nanotubes (CNTs) is an important subject of research. Recent attention has been paid to finding new strategies for the controlled growth of single-wall CNTs with a defined chirality. In addition, many potential applications require multiwall CNTs (MWCNTs) to grow vertically from the substrate and the interface property is crucial. Here, we report for the first time that MWCNTs can grow directly from the surface of a substrate by epitaxy, based on the experimental study of individual multiwall carbon nanotubes on a large-area stainless steel substrate, which is a very useful system for electrical and mechanical applications. In particular, evidence is given of the lattice matching between the MWCNT and the lattice of a hexagonal Cr2O3: (Fe, Mn) film formed on the surface of the substrate. Furthermore, a method is developed to increase the density of the MWCNTs; a mechanism of simultaneous top and bottom growth is proposed. The resultant significantly improved electrical transport and field emission properties are also presented, showing the Ohmic contact for electrical conduction and high performance in resisting the catastrophic cold-cathode vacuum breakdown of the CNTs.