AI Article Synopsis
- A chemical vapor deposition (CVD) process was developed for growing carbon nanotubes (CNTs) on porous alumina substrates, focused on optimizing gas flow and temperature through simulations.
- The gas phase during the CVD process was analyzed using molecular-beam quadrupole mass spectroscopy at high temperatures, specifically during the ferrocene reaction.
- Field-emission properties of the CNTs were explored, revealing that denser CNT populations achieved high emitter densities, while well-anchored CNTs in smaller pores produced the highest current densities under both direct current and pulsed conditions.
Article Abstract
We have developed a chemical vapor deposition (CVD) process for the catalytic growth of carbon nanotubes (CNTs), anchored in a comose-type structure on top of porous alumina substrates. The mass-flow conditions of precursor and carrier gases and temperature distributions in the CVD reactor were studied by transient computational fluid dynamic simulation. Molecular-beam quadrupole mass spectroscopy (MB-QMS) has been used to analyze the gas phase during ferrocene CVD under reaction conditions (1073 K) in the boundary layer near the substrate. Field-emission (FE) properties of the nonaligned CNTs were measured for various coverages and pore diameters of the alumina. Samples with more dense CNT populations provided emitter-number densities up to 48,000 cm(-2) at an electric field of 6 V microm(-1). Samples with fewer but well-anchored CNTs in 22-nm pores yielded the highest current densities. Up to 83 mA cm(-2) at 7 V microm(-1) in dc mode and more than 200 mA cm(-2) at 11 V microm(-1) in pulsed diode operation have been achieved from a cathode size of 24 mm2.
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| http://dx.doi.org/10.1002/smll.200600595 | DOI Listing |
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