Abstract Submitted to the    NANOTUBE'06 Conference:

Epitaxial Approaches to Carbon Nanotube Organization

Ernesto Joselevich

Department of Materials and Interfaces, Weizmann Institute of Science

ernesto.joselevich@weizmann.ac.il

I. CVD Synthesis of Carbon Nanotubes

The organization of carbon nanotube arrays on surfaces is a critical prerequisite for their large-scale integration into nanocircuits. In this presentation we will provide an overview of the recent advances toward the controlled formation of organized nanotube structures guided by different crystal surfaces, their morphologies and the possible mechanisms of their formation. We found that single-wall carbon nanotubes (SWNTs) catalytically produced on miscut c-plane sapphire wafers grow along the 0.2 nm-high atomic steps of the vicinal alpha-Al₂O₃ (0001) surfaces, yielding highly aligned, dense arrays of discrete nanotubes [1]. The nanotubes reproduce the atomic features of the surface, including steps and kinks. We also demonstrate the aligned growth of SWNTs by periodically nanofaceted surfaces, leading to the formation of either unprecedentedly straight and parallel nanotubes, or to wavy nanotubes loosely conformal to sawtooth-shaped faceted nanosteps [2]. It is also possible to create carbon nanotube crossbar arrays in one growth step by simultaneous nanofacet-directed and field-directed growth in perpendicular directions. Lattice-oriented, atomic step-templated and nanofacet-directed nanotube growth may be rationalized as nanotube-extended versions of incommensurate lattice-directed epitaxy, ledge-directed epitaxy, and graphoepitaxy, respectively. These different modes of “nanotube epitaxy” open up new possibilities for assembling nanotube architectures from the bottom up by surface engineering. We will as well show some unprecedented - and at times funny - nanotube structures, which form by other modes of nanotube epitaxy, not yet fully understood. We will stress that in the same way as epitaxy has advanced materials science and technology, nanotube epitaxy could advance nanotube science and technology.

[1] Ismach, A; Segev, L.; Wachtel, E.; Joselevich, E. Angew. Chem. Int. Ed. 2004, 43, 6140.
[2] Ismach, A; Kantorovich, D.; Joselevich, E. J. Am. Chem. Soc. 2005, 127, 11554.

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