Anisotropic electronic transport in highly aligned carbon nanotube films

Electronic transport in carbon nanotube (CNT) networks has recently attracted much renewed interest due to the numerous advancements in controlling, sorting, and aligning CNTs. Understanding the roles of intra-tube and inter-tube transport in these systems is fundamentally important both from basic and applied points of view. We have studied samples of ultra-long and highly-aligned CNTs grown by CVD and laid down on Si/SiO2 substrates. We designed and fabricated a novel device structure in which we can separately study intra-tube and inter-tube transport. In the intra-tube configuration, ends of ultra-long CNTs were contacted and the current parallel to the alignment direction was measured, whereas, in the inter-tube configuration, transport perpendicular to the alignment direction was probed. We studied the magnetic field and temperature dependence of the resistance between 0.3 K and 300 K, revealing an interesting evolution of transport regimes as for the localization of charge carriers. Preliminary results of photoconductivity measurements will also be presented.