RESUMEN
Both fullerenes and single-walled carbon nanotubes (SWNTs) exhibit many advantageous properties. Despite the similarities between these two forms of carbon, there have been very few attempts to physically merge them. We have discovered a novel hybrid material that combines fullerenes and SWNTs into a single structure in which the fullerenes are covalently bonded to the outer surface of the SWNTs. These fullerene-functionalized SWNTs, which we have termed NanoBuds, were selectively synthesized in two different one-step continuous methods, during which fullerenes were formed on iron-catalyst particles together with SWNTs during CO disproportionation. The field-emission characteristics of NanoBuds suggest that they may possess advantageous properties compared with single-walled nanotubes or fullerenes alone, or in their non-bonded configurations.
Asunto(s)
Cristalización/métodos , Fulerenos/química , Nanotecnología/métodos , Nanotubos de Carbono/química , Nanotubos de Carbono/ultraestructura , Sustancias Macromoleculares/química , Ensayo de Materiales , Conformación Molecular , Tamaño de la Partícula , Propiedades de SuperficieRESUMEN
A method to produce metal electrodes with a gap of a few nanometers with a highly focused electron beam in a transmission electron microscope (TEM) is described. With this method the electrical and geometrical characterization of the same particle is possible. The I-V characteristics of a gold particle trapped between such electrodes showed the expected single-electron tunneling behavior, with a Coulomb gap corresponding to the geometry of the particle as observed with high-resolution TEM.
Asunto(s)
Electroquímica/instrumentación , Oro/análisis , Oro/química , Ensayo de Materiales/instrumentación , Microelectrodos , Microscopía Electrónica de Transmisión/métodos , Conductividad Eléctrica , Electroquímica/métodos , Electrones , Diseño de Equipo , Análisis de Falla de Equipo , Ensayo de Materiales/métodos , Propiedades de SuperficieRESUMEN
We fabricated three-terminal devices with conjugated molecules. Two different device layouts were used to measure both very short molecules (with one or two benzene rings) and relatively long ones (as long as 8 nm). To achieve an optimum gate effect, we used aluminum gates covered with a very thin native oxide layer. Molecules with thiol end groups were positioned between the source and drain electrodes by self-assembly. The device yield was low for short molecules, most likely due to defects in the self-assembled monolayers. Most of the devices made with short molecules did not show any gate effect at all; a small gate effect was only observed in two samples made with 1,3-benzenedithiol. Some devices showed clear negative differential conductance peaks. In some devices made with long molecules, we observed a small change of conductance with gate voltage.
