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Pulse laser ablation and subsequent laser nanostructuring at room temperature has been employed to produce nanostructured Ni on SiO 2 /Si substrates for catalytic growth of carbon nanotubes. The resultant nanostructured surface is seen to consist of nanometer sized hemispherical droplets whose mean diameter is controlled by the initial metal thickness, which in turn is readily controlled by the number of laser pulses. Vertically aligned multiwall carbon nanotube mats were then grown using conventional plasma enhanced chemical vapor deposition. We show that within a single processing technique it is possible to produce the initial metal-on-oxide thin film to a chosen thickness but also to be able to alter the morphology of the film to desired specifications at low macroscopic temperatures using the laser parameters. The influence of the underlying oxide is also explored to explain the mechanism of nanostructuring of the Ni catalyst.

Optically transparent and electrically conductive single-walled carbon nanotube (SWNT) thin films were fabricated at room temperature using a dip-coating technique. The film transparency and sheet resistance can be easily tailored by controlling the number of coatings. Aminopropyltriethoxysilane (APTS) was used as an adhesion promoter and, together with surfactant Triton X-100, greatly improved the SWNTs coating. Only five coats were required to obtain a sheet resistance of 2.05 [Formula: see text] and film transparency of 84 %T. The dip-coated film after post-deposition treatment with nitric acid has a sheet resistance as low as 130 [Formula: see text] at 69 %T. This technique is suitable for large-scale SWNT coating at room temperature and can be used on different types of substrates such as glass and plastics. This paper will discuss the role of the adhesion promoter and surfactant in the coating process.

Low threshold fields of 1.6 V/μm and 2.6 V/μm were obtained for field emission from multiwalled carbon nanotubes and boron-doped multiwalled carbon nanotubes embedded in polystyrene, respectively. A Fowler–Nordheim analysis of the results together with sheet resistivity data illustrate that the higher carbon nanotube concentrations in a polystyrene matrix result in larger effective emission areas, at the expense of higher operating threshold fields.

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The electron field emission of carbon nanotube ͑CNT͒/boron-doped diamond ͑BDD͒/carbon felt electrodes ͑CNT/BDD/felt͒ have been investigated. The composite electrode was initially prepared with the growth of BDD on carbon felt and the subsequent growth of CNT by chemical decomposition of methanol. The composite electrodes were characterised using scanning electron microscopy and transmission electron microscopy. For the CNT/BDD/felt samples, the electron field emission was observed at macroscopic fields as low as 1.1 V m −1 . The emission current versus time plot shows significant potential for future field emission applications. © 2006 American Institute of Physics. ͓DOI: 10.1063/1.2178247͔ Diamond thin films are a class of carbon materials that have been used for electron field emission devices since 1991. 1 Its electron emission properties depend on several factors, such as the work function, grain boundaries, 2 and small protuberances. [3][4][5][6][7] For example, it has been shown that the boundaries between grains, sites rich in sp 2 hybridization, emit electrons more easily than the diamond facets of boron-doped diamond ͑BDD͒ polycrystalline films. 7 Interestingly, despite boron being an acceptor state in diamond it appears to enhance the electron emission properties of the material. We believe this is based on the substrate playing an important role in the emission process of diamond films. In fact, it has been observed that better emission results from chemical vapor deposited diamond films grown on SnO 2 instead of silicon, suggesting that the electron supply layer or substrates plays an active role in the emission process. 8 However, despite the well-known attractive properties of diamond ͑negative electron affinity, thermal, mechanical, and chemical inertness͒, there are still several problems in the production of field emission devices based on this material associated with obtaining high current densities from emitters, obtaining uniform microstructures, etc., which affect long-term stability. 9 In addition, diamond films, as well as other carbon materials which have been used for emission, are subject to thermal effects at the interface between the substrate and the carbon film. The presence of heating at the interface of the film and substrate generates different mechanical stresses on the film. This will increase the resistance and/or the voltage barrier needed to maintain electron emission at low voltages for an extended periods of time.In order to circumvent the above problem, we present here an approach based on a combination of carbon nanotubes ͑CNTs͒ and BDD films mounted on a carbon felt to obtain reproducible electron emission at low fields. BDD mounts on a carbon felt have previously been explored for electrochemical applications. 10,11 CNTs grown on BDD films, as described in this letter, is a further interesting technique to increase its potential uses.The felt substrate was obtained from carbonization of polyacrinitrile at 2000°C. The obtained carbon fibers have a diameter of around 10...

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