Methane chemical vapor deposition on transition metal/GaAs samples – a possible route to Haeckelite carbon nanotubes? |
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Authors: | Michael J Burek Thorsten Hesjedal |
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Institution: | 1. School of Engineering and Applied Sciences, Harvard University, , Cambridge, MA, 02138 USA;2. Waterloo Institute for Nanotechnology, University of Waterloo, , Waterloo, Ontario, N2L?3G1 Canada |
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Abstract: | We present a systematic study of atmospheric chemical vapor deposition growth of carbon nanotubes (CNTs) on patterned, transition metal/GaAs samples employing methane as the carbon feedstock. Controlled CNT growth was found to occur from the exposed metal‐semiconductor interface, rather than from the metal or semiconductor surfaces themselves. A fast sample loading system allowed for a minimization of the exposure to high temperatures, thereby preventing excessive sample damage. The optimum growth temperature for CrNi/GaAs interfaces is 700 °C (at a methane flow rate of 700 sccm). Possible growth scenarios involving the Ni–As–Ga system and its interaction with C is discussed. Raman spectroscopy of the CNTs revealed the presence of pentagon–heptagon defects. Closer analysis of the spectra points towards a mixture of so‐called Haeckelite CNTs. Copyright © 2011 John Wiley & Sons, Ltd. |
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Keywords: | carbon nanotubes chemical vapor deposition Raman spectroscopy Haeckelite structures |
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