The electronic properties of fullerene tubules have been predicted to depend strongly on their helical structure and radius. This has lead suggestions of using fullerene tubules as nanoscale electronic device components, including electrically conducting wires and Schottky diodes. As opposed to traditional metal interconnects, however, tubules are known to exhibit buckles and other nonlinear distortions which may influence their electrical properties. This in turn may limit possible nanoscale electronic device designs utilizing tubules.
To determine the influence of various structural distortions on the electronic properties of nanotubules, tight-binding calculations were carried out on a series of deformed fullerene tubules. These distortions included large uniaxial strains, isolated buckles arising from tubule bending, and flattening of tubules due to surface adhesive forces. The calculations predict a number of properties important to the use of tubules in nanoscale electronic devices, including the formation of radical gap states localized near nonlinear buckles in semiconducting tubules, band gap opening and closing due to large uniaxial strains, and significant changes in the density of states (and hence the conductivity) due to tubule flattening on substrates arising from weak adhesive forces. The results of these calculations and their implications for tubule-based electronic device designs will be discussed.
Sponsored by the NASA-Ames Computational Nanotechnology Program, the National Science Foundation, and the Office of Naval Research.