Aggregation properties of carbon nanotubes at interfaces

Single-walled carbon nanotubes (SWNTs) are emerging as promising candidates for molecular electronic device components. However, to obtain individual SWNTs and to place them controllably at interfaces remains a major hurdle. This is crucial because transport depends dramatically and subtly on the relative orientation of wires. We study theoretically the aggregation of dispersed individual SWNTs on a surface. We pay particular attention to the anisotropic orientational dependence of the van der Waals (vdW) interaction between tubes as well as that of the tube with the surface. We find that at experimentally relevant regimes, tubes form clusters of different sizes that depend on the density. Even for very low densities, individual tubes are improbable. (C) 2002 Elsevier Science B.V. All rights reserved.