Yutaka Ohno

The optical transition energies, ${E}_{11}$ and ${E}_{22}$, of single-walled carbon nanotubes (SWNTs) suspended in air have been investigated for 20 species by photoluminescence and excitation spectroscopies. We have studied the environmental effects in photoluminescence by comparing our results with those for the SWNTs wrapped by sodium-dodecyl-sulfate (SDS), as reported by Weisman and Bachilo [Nano Lett. 3, 1235 (2003)]. The energy differences between air-suspended and SDS-wrapped SWNTs, $\ens

Abstract The dependence of optical transition energies in single‐walled carbon nanotubes (SWNTs) on environmental dielectric constant ( ε env ) have been investigated in the range of ε env from 1.0 to 37, by immersing SWNTs bridged overtrenches in various organic solvents by means of photoluminescence (PL) and the excitation spectroscopies. With increasing ε env , both E 11 and E 22 exhibited a redshift by several tens meV and a tendency to saturate at a ε env ∼ 5 without an indication of signif

We have proposed a possibility of chirality assignment of individual single-walled carbon nanotubes in nanotube field-effect transistors (FETs) by micro-photocurrent spectroscopy. The nanotube FETs were fabricated by utilizing position-controlled nanotube growth technique using alcohol chemical vapor deposition. Photocurrent signal that originated from a single single-walled carbon nanotube was obtained by using microscopic optical measurement system. A peak was observed at 1.73 eV in the photoc

Position-controlled carbon nanotube field effect transistors (FETs) have been fabricated by using patterned catalysts and chemical vapor deposition. A double-layer metal of platinum and cobalt was used as the catalyst. The use of a mixture of ethanol and argon as the source gas was effective for obtaining FETs with good characteristics. Coulomb oscillation was observed at room temperature. 76% of the fabricated devices showed FET operation. The characteristics of FETs with metallic nanotubes wer

We have studied the photoluminescence (PL) of individual single-walled carbon nanotubes (SWNTs) placed in field-effect transistor structures. The SWNTs were suspended in the air so that strong PL was obtained. When an external bias voltage was applied to the device, no spectral changes could be detected, but the intensity drastically increased or decreased. This behaviour is explained by the injection/extraction of carriers from/to the electrodes by the electric field. In the case of p-type FETs

Electrochemical sensors based on carbon nanotubes (CNTs) have great potential for use in wearable or implantable biomedical sensor applications because of their excellent mechanical flexibility and biocompatibility. However, the main challenge associated with CNT-based sensors is their uniform and reproducible fabrication on the flexible plastic film. Here, we introduce and demonstrate a highly reliable technique to fabricate flexible CNT microelectrodes on a plastic film. The technique involves