Nanoscale Mapping of Resistivity and Charge Trap Activities in Carbon Nanotube-based Nanostructures

We report a method for the nanoscale mapping of resistivity and charge trap activities in carbon nanotube (CNT)-based nanostructured films such as metallic single walled carbon nanotube (m-SWCNT) networks embedded in gold thin films. In this method, a conducting probe made a direct contact with CNT-based nanostructured films, and it was utilized to measure the maps of electrical currents and noises. The measured maps were analyzed to estimate the nanoscale variation of resistivity (ρ) and the density distribution of charge traps (N_eff). For example, a hybrid film composed of m-SWCNT networks and gold films exhibited 300% improved conductivity and significantly reduced charge trap densities compared to that of pristine gold films. Interestingly, we found that the ρ and N_eff on both CNT/gold and pristine gold regions exhibited a scaling behavior like ρ ∝ N_eff^0.5, indicating hopping charge conductions and noise characteristics of the hybrid films. Since our method allows one to map the resistivity and charge trap activities with a nanoscale resolution, it can be a powerful tool for a basic study of nanoscale charge transport phenomena and a practical application based on nanostructured channels.