Impact of carbon nanotube length on electron transport in aligned carbon nanotube networks

Here, we quantify the electron transport properties of aligned carbon nanotube (CNT) networks as a function of the CNT length, where the electrical conductivities may be tuned by up to 10× with anisotropies exceeding 40%. Testing at elevated temperatures demonstrates that the aligned CNT networks have a negative temperature coefficient of resistance, and application of the fluctuation induced tunneling model leads to an activation energy of ≈14 meV for electron tunneling at the CNT-CNT junctions. Since the tunneling activation energy is shown to be independent of both CNT length and orientation, the variation in electron transport is attributed to the number of CNT-CNT junctions an electron must tunnel through during its percolated path, which is proportional to the morphology of the aligned CNT network.
United States. Army Research Office (contract W911NF-07-D-0004)
United States. Army Research Office (contract W911NF-13-D-0001)
United States. Air Force Office of Scientific Research (AFRL/RX contract FA8650-11-D-5800, Task Order 0003)
National Science Foundation (U.S.) (NSF Award No. ECS-0335765)
United States. Dept. of Defense (National Defense Science and Engineering Graduate Fellowship)