Dominant role of tunneling resistance in the electrical conductivity of carbon nanotube--based composites

The effect of nanotube/nanotube contact resistance on the electrical conductivity of carbon nanotube–based nanocomposites is studied. The tunneling resistance due to an insulating film of matrix material between crossing nanotubes is calculated by assuming a rectangular potential barrier in the insulating film. Monte Carlo simulations indicate that the tunneling resistance plays a dominant role in the electrical conductivity of composites, and the maximum tunneling distance is found to be about 1.8 nm. Electrical conductivities of composites with inplane random distributions of carbon nanotubes follow the scaling law and the critical exponent depends on the level of contact resistance.