Optimized contact configuration for the study of transport phenomena in ropes of single-wall carbon nanotubes

The study of the intrinsic transport properties of carbon nanotubes suffers from the difficulties in fabricating noninvasive contacts. Here, we present a scheme for the investigation of transport phenomena in metallic single-wall carbon nanotubes by means of a special four-terminal measurement configuration. To suppress the impact of the contacts on the measured conductance in a tube, we found a combination of top and bottom contacts to the rope of single-wall nanotubes to be most appropriate. Our experimental findings demonstrate that a linear decrease of the sample resistance can be observed under these circumstances without the common increase of resistance for decreasing temperatures.