A 0.4 mm long semiconducting single-walled carbon nanotube is doped into n type by potassium ~K! vapor. Electrical measurements of the doped nanotube reveal single-electron charging at temperatures up to 160 K. The K-doped sample manifests as a single quantum dot or multiple quantum dots in series depending on the range of applied gate voltage. This is explained by an inhomogeneous doping profi...

We demonstrate the efficient chemical vapor deposition synthesis of single-walled carbon nanotubes where the activity and lifetime of the catalysts are enhanced by water. Water-stimulated enhanced catalytic activity results in massive growth of superdense and vertically aligned nanotube forests with heights up to 2.5 millimeters that can be easily separated from the catalysts, providing nanotub...

The role of water in carbon feed on the surface-guided growth of horizontally aligned single-walled carbon nanotubes (HA-SWCNTs) was investigated. It is shown that the amount of water can be optimized to favor HA-SWCNT growth, which is proposed to be due to selective etching of carbon deposits at carbon–metal interface. Without water, nanotube–nanotube interaction and carbon accumulation at the...

We demonstrate a fully tunable diode structure utilizing a fully suspended single-walled carbon nanotube. The diode's turn-on voltage under forward bias can be continuously tuned up to 4.3 V by controlling gate voltages, which is ∼6 times the nanotube band gap energy. Furthermore, the same device design can be configured into a backward diode by tuning the band-to-band tunneling current with ga...

Rayleigh scattering spectra were obtained from individual single-walled carbon nanotubes with the use of a laser-generated visible and near-infrared supercontinuum. This diagnostic method is noninvasive and general for nanoscale objects. The approach permits clear identification of excited states in arbitrary metallic and semiconducting nanotubes. We analyzed spectral lineshapes in relation to ...

We studied the optical properties of aligned carbon nanotube mats for photonic device applications. We employed ab-initio density functional calculations in the linear combination of atomic orbital formalism. The calculated dielectric functions of the semiconducting carbon nanotube mats show a strong anisotropy when the electric field of the light is parallel or perpendicular to the tube axes. ...

Highly ordered anodic TiO2 nanotube arrays fabricated by electrochemical anodization were sensitized with ruthenium dye N-719 to yield dye-sensitized TiO2 nanotube solar cells. Rational surface treatments on photoanode TiO2 nanotubes markedly improved the device performance. With TiCl4 treatment, in conjunction with oxygen plasma exposure under optimized conditions, dye-sensitized TiO2 nanotube...

In this study we investigate the insertion of pioglitazone, a Thiazolidinedione, into the two different sizes of Carbon nanotub. It was shown that the insertion of pioglitazone into the carbon nanotube in a water solute environment could be related to the diameter of the nanotube and in the flow of the waters via hydrophilic interactions. This encapsulated drug-carbon nanotube molecule can be f...

We improve the conversion efficiency of Ag2S quantum dot (QD)-sensitized TiO2 nanotube-array electrodes by chemically depositing ZnO recombination barrier layer on plain TiO2 nanotube-array electrodes. The optical properties, structural properties, compositional analysis, and photoelectrochemistry properties of prepared electrodes have been investigated. It is found that for the prepared electr...

We report biodetection of the thyroid hormone triiodothyranine (T3) using carbon nanotube field-effect transistors. T3 molecules bind non-covalently the semiconducting nanotube and donate electrons to the nanotube lattice, thereby altering its electronic characteristics via chemical doping. The effect is semi-reversible by rinsing the transistors with the T3 solvent without the biomolecule. The...