Towards Molecular Modification of Carbon Nanotube Junctions in Thin Film Transistors

Carbon nanotube thin film transistors have recently been used on flexible and transparent substrates for applications in integrated circuits and display drivers. Such networks are of interest due to their relatively high carrier mobility and mechanical flexibility. However, the I _ON /I _OFF ratio of these networks varies inversely with the carrier mobility, and advances in reducing the electrical and thermal resistance of nanotube junctions are needed to improve the device performance and reliability. The objective of this work is create a process to improve CNT TFT device performance by using 0-dimensional molecules to modify the physical properties of the nanotube junctions. Our preliminary data indicate C60 fullerenes deposited on CNT TFTs results in decreased carrier mobility and a reduced I _ON / I _OFF ratio. This is likely a result of an n-type doping effect by the C60 molecules on the otherwise p-type CNTs, leading to increased p-n junctions throughout the CNT network. While this effect is detrimental to p-type CNT TFT device performance it highlights the potential of 0-dimensional molecules in tuning the transport properties of CNT networks for applications such as transparent electrodes, chemical sensors, and transistors.