on sapphire surfaces
Synthesis of well-aligned and ultralong single-wall carbon nanotubes (SWNTs)
on a solid substrate is the first step toward real application of CNTs to nano-scale devices. A stepped surfaces are usually used as a template for the growth of aligned CNTs. Recently, however, using chemical vapor deposition method, Ago et al. have reported that ultralong SWNT can be grown on sapphire surfaces along a certain
crystallographic direction . Although it is generally argued that the selective growth is related to the anisotropic arrangement of surface atoms, the physical and chemical origins are unknown yet. In this seminar, I present my first-principles calculations about the adsorption of CNTs on the sapphire surfaces. I explore the various adsorption
structures on two different crystallographic planes with different chemical compositions of the substrate. Analysis of the total energies reveals that the strong chemical interaction of the SWNT with the surface not the van der Waals interaction is responsible for the selective growth. The origins of the anisotropic interactions and
electronic structures are to be discussed in the seminar.
 Ago et al. Chem. Phys. Lett. 408, 433 (2005).