The electrical and optical properties of oriented Langmuir-Blodgett films of single-walled carbon nanotubes

Thin, transparent, electrically-conductive films containing single-walled carbon nanotubes have been fabricated using the Langmuir-Blodgett method. No additional surfactant was used and films up to 99 layers in thickness (300 nm) could readily be built-up. Both optical and electrical measurements revealed anisotropy in the film plane, suggesting alignment of the tubes during the deposition process. For the majority of films, DC conductivity measurements over the range 77-300 K showed an increase in the conductivity with increasing temperature, i.e. semi-conducting characteristics. However, some samples exhibited the opposite effect. Such metallic films reverted to semi-conducting behaviour following an electrical annealing process.