Four-terminal measurements of SWNTs using MWNTs as voltage electrodes

We report on electron transport measurements of single-wall carbon nanotubes in a four-terminal configuration with noninvasive voltage electrodes. The voltage drop is detected using multiwalled carbon nanotubes while the current is injected through nanofabricated Au electrodes. Measurements are carried at high temperature so that the four-terminal resistance directly gives the intrinsic resistance. The resistance is shown to result from weak disorder and from quantum interference effect corrections. In addition, we present Coulomb blockade measurements. The length of the quantum dot that is determined from the level spacing equals the separation between the Au electrodes.