Effect of Fe catalyst thickness and C2H2/H2 flow rate ratio on the vertical alignment of carbon nanotubes grown by chemical vapour deposition

A. Rizzo, R. Rossi, M.A. Signore, E. Piscopiello, L. Capodieci, R. Pentassuglia, T. Dikonimos, R. Giorgi

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Abstract

Carbon nanotubes (CNTs) were fabricated by Chemical Vapour Depositon using a C2H2/H2mixture. They were grown on Si/SiO2substrate with Fe film as catalyst, deposited using thermal evaporation technique. The aim of this work is to emphasize the role of the Fe catalyst thickness and the C2H2/H2flow rate ratio to grow vertically aligned CNTs by thermal CVD. In order to investigate these aspects, four Fe metal films with thickness of 2.5, 3.5, 7.5 and 16 nm were deposited on Si/SiO2substrate and CNTs were grown with different C2H2/H2flow rate ratios, from 5/95 to 30/70 by thermal CVD at 750 °C. Results showed that CNTs were not vertically aligned with 16 nm catalyst thickness for all flow rate ratios, while CNTs were always vertically aligned for iron thickness less than 3.5 nm and vertically aligned only for a C2H2/H2flow rate ratio greater than 20/70 for the 7.5 nm catalyst thickness. Morphology and structural information about CNTs and Fe metal clusters were provided by field emission gun-scanning electron microscopy (FEG-SEM), atomic force microscopy (AFM) and high resolution transmission electron microscopy (HRTEM). Our results also indicate that for each flow rate ratio exists a critical thickness of iron catalyst under which vertically aligned CNTs are obtained. © 2008 Elsevier B.V. All rights reserved.
Original languageEnglish
Pages (from-to)1502 - 1505
Number of pages4
JournalDiamond and Related Materials
Volume17
Issue number7-10
DOIs
Publication statusPublished - Jul 2008
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Materials Chemistry
  • Surfaces, Coatings and Films
  • Surfaces and Interfaces

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