Room-temperature ultraviolet lasing in semiconductor nanowire arrays has been demonstrated. The self-organized, <0001> oriented zinc oxide nanowires grown on sapphire substrates were synthesized with a simple vapor transport and condensation process. These wide band-gap semiconductor nanowires form natural laser cavities with diameters varying from 20 to 150 nanometers and lengths up to 10 micrometers. Under optical excitation, surface-emitting lasing action was observed at 385 nanometers, with an emission linewidth less than 0.3 nanometer. The chemical flexibility and the one-dimensionality of the nanowires make them ideal miniaturized laser light sources. These short-wavelength nanolasers could have myriad applications, including optical computing, information storage, and microanalysis.

Highly sensitive nanowire switches have been created using ZnO nanowires. The light‐ induced conductivity increase, which is extremely sensitive to ultraviolet light, allows the reversibly switching of the nanowires between the “OFF” and “ON” states by an optical gating phenomenon analogous to the commonly used electrical gating. The Figure shows a field‐emission SEM image of a 60 nm ZnO nanowire bridging four Au electrodes.

The investigation of the field emission (FE) properties of carbon nanotube (CNT) films by a scanning anode FE apparatus, reveals a strong dependence on the density and morphology of the CNT deposit. Large differences between the microscopic and macroscopic current and emission site densities are observed, and explained in terms of a variation of the field enhancement factor β. As a consequence, the emitted current density can be optimized by tuning the density of CNTs. Films with medium densities (on the order of 107 emitters/cm2, according to electrostatic calculations) show the highest emitted current densities.

No abstract

2001 nanotechnology nanotechnology V 1505 -254Room-Temperature Ultraviolet Nanowire Nanolasers.-(0001)oriented ZnO nanowires are grown on sapphire substrates by a simple vapor transport and condensation process using Au thin films as catalysts. These nanowires form natural laser cavities with diameters varying from 20 to 150 nm and lengths up to 10 µm. Under optical excitation, surface-emitting lasing action is observed at 385 nm, with an emission linewidth less than 0.3 nm. The chemical flexibility and the one-dimensionality of the nanowires make them ideal miniaturized laser light sources. These short-wave-length nanolasers could have many applications, including optical computing, information storage, and

No abstract

No abstract

Tuning the electron emission properties of films containing carbon nanotubes is demonstrated. Microcontact printing is used to pattern silicon substrates with catalyst, which facilitates the growth of the carbon nanotubes by the chemical vapor deposition of acetylene. The catalyst is applied in liquid form to an elastomeric stamp prior to transfer to the substrate, and varying the concentration of the catalyst on the solution (“the ink”) directly influences the density of nanotubes on the patterned film.