Growth of Carbon Nanotubes on Patterned Catalysts: Towards a Carbon Nanotechnology

G. A. J. Amaratunga , M. Chhowalla, K. Teo, C. Ducati, I. Alexandrou, N. L. Rupesinghe, A. Ferrari, W. I. Milne and J. Roberstson, Engineering Dept.,

D. Roy and T. W. Clyne, Dept. of Materials Science,

D. Hasko, Microelectronics Research Centre, Cavendish Laboratory,

Cambridge University, Cambridge CB2 1PZ, UK.

A. J. Papworth and C. J Kiely, Engineering Dept., Materials Science and Engineering,

University of Liverpool, Liverpool L69 3BX, UK.

It is now 10 years since the TEM observations of Ijima which gave rise to the radical re-examination of graphitic carbon behaviour on the nanometer scale. The scientific understanding of the expected ( and observed) mechanical and electronic behaviour of carbon nanotubes gained over the last decade points to it being a near ideal system for nanoscale mechanical and electronic devices. This in turn has inspired may groups world wide to attempt to develop a technology which will allow the properties of carbon nanotubes to be exploited.

The highest quality nanotubes available at present are the single wall type produced through laser ablation. From a technological perspective they are , however, not optimal as it is necessary to purify them in solution, and then assemble them into desired structures. The latter has proved to be a non-trivial task.

The alternative approach is to use a chemical vapour deposition ( CVD) process to grow where they are required for the final device structure. This process has been approached on the basis of the controlled and defined placement of the catalyst on a substrate. However, the quality of CNTs and their orientation have been difficult to control in the CVD process.

Here we report our latest results which show that the CVD process with plasma enhancement can be used to grow oriented nanotubes with very high definition and selectivity over large areas. The methods of catalyst control required to achieve this are discussed. The quality of the carbon nanotubes can also be controlled to some extent. In fact we show evidence for the possibility of synthesising single wall carbon nanotubes by the CVD method. We also show the differences in the catalytic process under plasma conditions which lead to the alignment of CNTs. Taken together, the results show that the initial steps required for the development of a technology for electronic and mechanical devices exploiting the properties of CNTs are now in place.