Carbon nanotubes – manufacturing by plasma enhanced CVD.

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angličtina

The microwave (mw) plasma torch at atmospheric pressure has been studied for carbon nanotubes (CNT) synthesis. The depositions were carried out on silicon substrates with 5-15 nm thin iron catalytic overlayers from the mixture of argon, hydrogen and methane. The optical emission spectroscopy of the torch showed the presence of C2 and CH radicals as well as carbon and hydrogen excited atoms. The vicinity of the substrate influenced the relative intensities and increased the emission of C2. For fixed mw power, the temperature of the substrate strongly depended on its position with respect to the nozzle electrode and on the gas mixture, particularly the amount of H2. The speed of the substrate heating during an early deposition phase had a significant effect on the CNT synthesis. An abrupt increase of the temperature at the beginning increased the efficiency of the CNT synthesis. Areas of dense straight standing CNTs, 30 nm in average diameter, with approximately the same sized iron nanoparticles on their tops were found in accordance with the model of growth by plasma enhanced chemical vapour deposition. However, the deposition was not uniform and a place with only several nanometers thick CNTs grown on much larger iron particles ware also found. Here, talking into account the gas temperature in torch, 3100-3900 K, we can see similarities with the ‘dissolution-precipitation’ model of the CNT growth by high temperature methods, arc or laser ablation.

plasma enhanced CVD.

Lenka Zajíčková, Marek Eliáš, Jiřina Matějková, Richard Ficek, Radimír Vrba

2005

23. 9. 2005

Technological Institute of Chania

Chania

80-214-3042-7

Intensive Training Programme in Electronic System Design

155

157

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