Calculations based on density-functional theory were used to model armchair carbon nanotubes existing in isolation, close-packed into nanopores, and lying prone on both the hydrogen-terminated and clean (001) surfaces of diamond. In the combined nanotube: diamond systems, the electronic band structures were indicative of electron transfer from the hydrogen-terminated diamond to the physisorbed nanotubes; that is, carbon nanotubes-like C60 appeared to be capable of transfer doping diamond p type. Total-energy comparisons with separated systems suggested that the nanotubes were positively bound to the diamond substrate. Diffusion techniques were used to model movement of the (7,7) nanotube across the hydrogen-terminated diamond surface, with the results suggesting that this substrate presents a rather smooth energy surface to the nanotube; this was consistent with the fact that no covalent bonding across the interface was found. For comparison, the same nanotube was modelled above a completely clean diamond (001) surface, and while the nanotube remains bound to the diamond substrate, there was no charge transfer across such an interface.

Carbon Nanotubes and Their Interaction with the Surface of Diamond. Sque, S.J., Jones, R., Öberg, S., Briddon, P.R.: Physical Review B, 2007, 75[11], 115328