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Growth, Nitrogen Doping and Characterization of Isolated Single-Wall Carbon Nanotubes using Liquid Precursors
Published online by Cambridge University Press: 01 February 2011
Abstract
Isolated single wall carbon nanotubes (SWNTs) were prepared on bare quartz and SiO2/ Si substrates using chemical vapor deposition (CVD) in which a liquid precursor, such as xylene, was used as the carbon source. The coverage of isolated SWNTs on the substrates was controlled by adjusting the concentration of iron (III) nitrate nonahydrate/2-propanol solution which provided the Fe seed catalyst particles. Micro-Raman spectra were obtained using the 514.5 nm excitation which showed the typical tangential band around 1590 cm−1 for semiconducting nanotubes. The radial breathing mode (RBM) frequencies ranged between 150 to 240 cm−1 and the estimated tube diameters are in good agreement with those obtained from atomic force microscope (AFM) images. In our synthesis approach controlled doping of isolated SWNTs with nitrogen was achieved by mixing appropriate amount of acetonitrile with xylene. As the nitrogen concentration in the feed was increased from 0 – 33 at. %, the RBM intensity decreased dramatically while the intensity of the D-band increased gradually relative to that of the G-band. Interestingly, the D' band was observed for the first time in the Raman spectrum of carbon nanotubes when the nitrogen concentration reached ∼2–3 at. %.
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- Copyright © Materials Research Society 2005