Simple use of SiO2 film thickness for the control of carbon nano-tube diameter during ferrocene catalyzed CVD growth

N. Chopra, P. D. Kichambare, R. Andrews, B. J. Hinds

Research output: Contribution to journalConference articlepeer-review

Abstract

Selective growth of carbon nano-tubes (CNT) on micron scale patterned substrates has been accomplished by taking advantage of the non-reactivity of ferrocene catalyst on H-terminated Si surfaces in a CVD process. Demonstrated here is that this phenomenon can be used to control the diameter of CNTs when sufficiently narrow lines of SiO2 surrounded by H-terminated Si are used. Narrow lines of SiO2 (12-60nm) are formed at the etched face of a Si/SiO2/Si multilayer structure. This allows the precisely controllable thickness of an SiO2 film to determine an exposed SiO2 line width. There is no need for e-beam lithography since film thickness determines nm-scale line dimensions. CNTs are then formed by CVD with a ferrocene/H2/Ar mixture at 700°C. CNTs are observed to grow only on the exposed SiO2 surface at the edge of the 'mesa' structure. CNT diameters of 13.2, 20.5, 34.2, 64.3nm are observed for SiO2 film thickness of 12, 19, 35, and 65 nm. The larger distribution of CNT diameter with increased line width is consistent with wider SiO2 linewidths not being able to affect smaller nucleation centers. These results are consistent with the use of self-assembly chemistry of iron catalyst onto nanoparticles of catalyst support.

Original languageEnglish
Pages (from-to)187-192
Number of pages6
JournalMaterials Research Society Symposium Proceedings
Volume739
DOIs
StatePublished - 2002
EventThree-Dimensional Nanoengineered Assemblies - Boston, MA, United States
Duration: Dec 1 2002Dec 5 2002

ASJC Scopus subject areas

  • Materials Science (all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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