The thermal conductivity of individual multiwalled carbon nanotubes was measured by utilizing the four-point-probe third-harmonic method, based on the fact that the third harmonic amplitude and phase as a response to applied alternate current at fundamental frequency, omega, can be expressed in terms of thermal conductivity and diffusivity. To this end, a microfabricated device composed of four metal electrodes was modified to manufacture nanometer-sized wires by using a focused ion beam source. A carbon nanotube could then be suspended over a deep trench milled by the focused ion beam, preventing heat loss to the substrate. Compared with the two-point-probe technique, a significant improvement in accuracy is assured by using four probes, because the contact contribution to the determination of the thermal conductivity is eliminated, making it possible to measure the correct signals of first and third harmonics. The multiwalled carbon nanotube was modeled as a one-dimensional diffusive energy transporter and its thermal conductivity was measured at room temperature under vacuum to be 300 +/- 20 W/mK.

The thermal conductivity of individual multiwalled carbon nanotubes (outer diameter of ∼45nm) was obtained by employing the 3-ω method. To this end, the third-harmonic amplitude as a response to the applied alternate current at fundamental frequency (ω) is expressed in terms of thermal conductivity. A microfabricated device composed of a pair of metal electrodes 1μm apart is used to place a single nanotube across the designated metal electrodes by utilizing the principle of dielectrophoresis. The multiwalled carbon nanotube was modeled as a one-dimensional diffusive energy transporter and its thermal conductivity was measured to be 650–830W∕mK at room temperature.

Two- and four-probe electrical measurements on individual tin oxide (SnO(2)) nanowires were performed to evaluate their conductivity and contact resistance. Electrical contacts between the nanowires and the microelectrodes were achieved with the help of an electron- and ion-beam-assisted direct-write nanolithography process. High contact resistance values and the nonlinear current-bias (I-V) characteristics of some of these devices observed in two-probe measurements can be explained by the existence of back-to-back Schottky barriers arising from the platinum-nanowire contacts. The nanoscale devices described herein were characterized using impedance spectroscopy, enabling the development of an equivalent circuit. The proposed methodology of nanocontacting and measurements can be easily applied to other nanowires and nanometre-sized materials.

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Ultrashort pulsed-laser radiation is an effective method for precision materials processing and surface nano-/micromodification because of minimal thermal and mechanical damage. This study demonstrates that controllable surface nanomachining can be achieved by femtosecond laser pulses through local field enhancement in the near-field of a sharp probe tip. Nanomachining of thin gold films was accomplished by coupling 800-nm femtosecond laser radiation with a silicon tip in ambient air. Finite-difference time-domain numerical predictions of the spatial distribution of the laser field intensity beneath the tip confirmed that the observed high spatial resolution is due to the enhancement of the local electric field. Possible structuring mechanisms and factors affecting this process are discussed. The present process provides an intriguing means for massive nanofabrication due to the flexibility in the substrate material selection, high spatial resolution of ∼10 nm (not possible with standard nanomachining techniques), and fast processing rates achievable through simultaneous irradiation of multiarray tips.