Small-diameter (1 to 7 nanometers) silicon nanowires (SiNWs) were prepared, and their surfaces were removed of oxide and terminated with hydrogen by a hydrofluoric acid dip. Scanning tunneling microscopy (STM) of these SiNWs, performed both in air and in ultrahigh vacuum, revealed atomically resolved images that can be interpreted as hydrogen-terminated Si (111)-(1 x 1) and Si (001)-(1 x 1) surfaces corresponding to SiH3 on Si (111) and SiH2 on Si (001), respectively. These hydrogen-terminated SiNW surfaces seem to be more oxidation-resistant than regular silicon wafer surfaces, because atomically resolved STM images of SiNWs were obtained in air after several days' exposure to the ambient environment. Scanning tunneling spectroscopy measurements were performed on the oxide-removed SiNWs and were used to evaluate the electronic energy gaps. The energy gaps were found to increase with decreasing SiNW diameter from 1.1 electron volts for 7 nanometers to 3.5 electron volts for 1.3 nanometers, in agreement with previous theoretical predictions.

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Arrays of oriented silicon carbide (SiC) nanowires are synthesized by reacting stable carbon nanotubes—which act as both template and reagent—with SiO. Field emission measurements on the nanowires indicate that the arrays are excellent field emitters, technologically useful field emission current densities being produced at very low electric fields. The results suggest that the oriented nanowires may have potential uses in vacuum microelectronic devices in addition to more conventional applications as strengthening in composites (replacing SiC whiskers, which have lower elasticity and strength).

Silicon nanowires (SiNWs) were synthesized using laser ablation. A continuous SiNW film was prepared by grinding the pieces of sponge-like SiNWs to powder, then dispersing and sticking the powder onto a Si wafer. The field emission characteristics of the SiNW film were studied based on current–voltage measurements and the Fowler–Nordheim equation. The electron field emission increased with decreasing diameter of SiNWs. A hydrogen plasma treatment of the SiNW film aimed at reducing the oxide overlayer improved the emission uniformity of the film.

Using a single nano-object measurement methodology that enables the correlation between size/morphology/structure and photoluminescence (PL) characteristics, we show that nanoribbons are an excellent model system to study single nano-objects. In particular, we measure the PL characteristics of optically pumped individual single-crystal zinc–sulfide nanoribbons. Small collection angle measurements show that nanoribbons form excellent optical cavities and gain medium with high (full width at half maximum<0.1 nm) lasing modes free of PL background even for a low pumping power density of 9 kW/cm2. Large collection angles add a broad PL component and obscure the correct high-quality lasing of the nanowires/nanoribbons.