Optimization of multi-walled carbon nanotube-metal contacts by electrical stressing.

We present experimental data on the contact resistances of three different metal probes, tungsten, palladium and indium, with chemical vapour deposited (CVD) multi-wall carbon nanotubes (MWCNTs). We demonstrate that there is an irreversible modification of the contacts following electrical stressing whereby the circuit resistance converges towards its optimal value prior to current-induced tube failure. Once the probe-MWCNT contact is broken, subsequent recontact experiments reveal that the circuit resistance returns to its initial high level, demonstrating that the modification occurs at the probe contact location and not elsewhere in the circuit. Contact studies with the different metals reveal that Pd metal provides the lowest resistance contact to the MWCNT in our sample.