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High-quality single-crystalline GaP nanowires were grown by a simple vapour deposition method and their electrical and opto-electric transport properties were studied. Structural studies showed that the GaP nanowires consisted of a core?shell structure with a single-crystalline GaP core and an outer gallium oxide (GaOx) layer of thickness ?nm. The individual GaP nanowires exhibited n-type field effects with an on/off ratio as high as 105 and their carrier mobilities are in the range of about 10?22?cm2?V?1?s?1 at room temperature. When the devices were exposed to an ultraviolet (UV) light source, the current in the nanowires increased abruptly to more than 103 times, and this was possibly due to carrier generation in the nanowires and de-adsorption of adsorbed O2? ions on the GaOx surface shell. The nanowires also showed good reversible switching actions between the high-?and low-resistance states.

On a single GaN nanowire, obtained by chemical vapour deposition, several Schottky-junction diodes were fabricated and their electrical transport properties were studied. Alternately attached metal electrodes of Al and Ti/Au formed a Schottky barrier junction (for Al) or an ohmic contact (for Ti/Au), resulting in several diodes on a single nanowire. The current–voltage measurements exhibited clear rectifying behaviour and no reverse-bias breakdown was observed up to the measured voltage, −5 V. The forward-bias threshold voltage was observed to decrease linearly with temperature, from 0.4 V at 280 K to 1 V at 10 K.

We report single step-like asymmetric magnetoconductance from a double-walled carbon nanotube single electron transistor contacted by ferromagnetic cobalt electrodes. The device conductance changed significantly when the direction of the applied magnetic field was reversed, but did not show the spin-valve-type double extrema feature near the coercive field of the electrodes. The magnetoconductance also showed quasi-periodic sign-reversing oscillations with respect to the applied bias. The bias-dependent oscillation of the magnetoconductance was compared with the quantum dot stability diagram for the device. As a result, it was confirmed that the asymmetric magnetoconductance was caused by the magneto-Coulomb effect.

We have fabricated MOS memory devices based on coil–rod–coil triblock molecules acting as quantum dots. Uniform molecular dots result in a discrete shift in the threshold voltage at room temperature, which is indicative of single-electron effects. Molecular scalability and low-power operation make the silicon-molecular hybrid device an attractive candidate for next-generation electronic devices.

Nanodevices using individual indium nitride nanowires are fabricated by e-beam lithography. The nanowires have diameters of 40-80 nm, lengths up to several tens of micrometres and single-crystalline nature. We observed ohmic I-V behaviour of InN nanowires above nearly 100 K, which is consistent with the pinning Fermi level of the metal electrode near the conduction band edge of InN nanowire. At low temperatures, the device shows typical semiconductor behaviour along with a quantum tunnelling effect through the Schottky barrier rather than thermally activated transport. The activation energy calculated above and below 80 K is 28.2 and 5.08 meV, respectively. We have also fabricated a photocurrent generation device using InN nanowires. The photocurrent of an acceptor-sensitizer dyad with di-(3-aminopropyl)-viologen (DAPV) and a Ru complex on an InN nanowires/ITO plate was 8.3 nA cm(-2), which increased by 62.7% compared to that without InN nanowire layers.

We have investigated the electric transport properties of individual In2O3 nanowire devices. We have found that the gate modulation characteristics depend strongly on the channel length. If the channel length is greater than 450 nm, the gate modulation curve exhibited field-effect transistor behavior with dominant n-channel current at room temperature. With the decrease of the channel length, the leakage current is increased due to the short-channel effect. For such short-channel devices, the gate modulation curve exhibited quasi-periodic current oscillations at low temperature, which are attributed to the Coulomb blockade of single-electron tunneling. Some devices showed two-fold periodicity in the Coulomb diamonds which may arise from the spin degeneracy of the single-particle energy levels.

We have studied electrical transport characteristics of individual double-wall carbon nanotubes (DWNT) under high bias voltages. As the bias voltage applied to the carbon nanotubes increases, the outermost shell of the DWNTs broke down sequentially, which enabled us to determine the current-carrying capacity of each shell. The maximum current-carrying capacity per shell was about 150??A, which is well above that of any other previous reports.