Frequency dependence of the structure and electrical behaviour of carbon nanotube networks assembled by dielectrophoresis

The statistical variations in the properties of carbon nanotubes and their contacts to metallic electrodes can be averaged by using networks of single-walled carbon nanotubes as sensing devices. Carbon nanotube networks have been assembled on microstructures with dielectrophoresis, using an inhomogeneous alternating electric field to attract carbon nanotubes onto the microelectrodes. The networks were assembled on identical microstructures using four different frequencies in the range 10 kHz–10 MHz. From structural and electrical characterization of the assembled structures, we found that at higher frequencies the assembled nanotubes align better with the electric field and are more free of impurities. We also found consistently lower resistances for networks assembled at higher frequencies, suggesting that a high assembly frequency may lead to better quality networks with low contact resistances.