We have measured IV curves of multiwalled carbon nanotubes using end contacts. At low voltages, the tunneling conductance obeys non-Ohmic power law, which is predicted both by the Luttinger liquid and the environment-quantum-fluctuation theories. However, at higher voltages we observe a crossover to Ohm's law with a Coulomb-blockade offset, which agrees with the environmentquantum-fluctuation theory, but cannot be explained by the Luttinger-liquid theory. From the high-voltage tunneling conductance we determine the transmission line parameters of the nanotubes.

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A three-terminal nanotube device was fabricated from two multiwalled nanotubes by pushing one on top of the other using an atomic-force microscope. The lower nanotube, with gold contacts at both ends, acted as the central island of a single-electron transistor while the upper one functioned as a gate electrode. Coulomb blockade oscillations were observed on the nanotube at sub-Kelvin temperatures. The voltage noise of the nanotube single-electron transistor (SET) was gain dependent as in conventional SETs. The charge sensitivity at 10 Hz was 6×10−4 e/Hz.

We have studied magnetic field and temperature dependence of electron transport in chemical vapor deposition synthesized highly resistive multiwalled carbon nanotubes. The analysis of the weak-localization magnetoresistance according to electron-electron interaction theories leads to very small mean free paths, ᐉ Ͻ10 nm. At lowest temperatures the sheet resistance is near R K ϭh/e 2 . Both of these observations suggest that our samples are close to the strong-localization limit.

We show that it is possible to construct low-noise single-electron transistors (SETs) using free-standing multiwalled carbon nanotubes. The 1/fα-noise of our devices, 6×10−6e/Hz at 45 Hz, is close in the performance to the best metallic SETs of today.