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New Hetero Silicon-Carbon Nanostructure Formation Mechanism

S. P. Songa, M. A. Crimpb, V. M. Ayres*, a, and Corey Collardc

aDept. of Electrical & Computer Engineering, Michigan State University,
East Lansing, MI 48824 USA

bDepartment of Chemical Engineering and Materials Science, Michigan State University,
East Lansing, MI 48824 USA

cDepartment of Nuclear Engineering and Radiological Sciences University of Michigan,
Ann Arbor, MI, 48109 USA

This is an abstract for a presentation given at the
10th Foresight Conference on Molecular Nanotechnology


We report on the simultaneous formation of silicon and carbon nanostructures in an inductively coupled plasma (ICP) system. ICP systems have unique scaling characteristics which enable very large area uniformity, making them potentially suitable for large volume production of nanotubes and nanostructures. Samples were prepared by forming a 10-20 nm thick Fe layer on a p-type (100) silicon substrate using laser ablation. Results over time periods of 1, 3, and 5 hours indicate that, as the Fe catalyst layer was broken up into islands by the action of the plasma, it served as a nano-mask for the etching of silicon, as well as the nucleation site for the growth of carbon nanostructures via the liquid-metal-solid (LMS) growth mechanism.

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Clockwise form Top Left: Carbon nanostructures grown for 2, and 5 hours; Heterostructure showing carbon nanostructure, tops of silicon nano-needles and junction; and Silicon nano-needle, side view.

The resulting silicon and carbon nanostructures were characterized using SEM, TEM with selected area diffraction (SAD), HR-TEM, and by micro-Raman and surface enhanced Raman spectroscopy (SERS). Multiwalled carbon nanostructures of approximate inner diameters 30-60 nm, outer diameters 90-140 nm, and micron-scale lengths were grown during the 1, 3, and 5-hour depositions. Silicon nanostructures of approximate lengths 0.4-1.0 µm, with base widths 10-100 nm, which tapered to a roughly 10 nm point at the tops, were formed, corresponding to the 1, 3, and 5 hour reactor times. Based on selected area diffraction, these were single crystal silicon nanostructures with [100] orientation along the long axis. The observed Si structures were consistent with formation by a controlled etching mechanism of the (100) silicon substrate. An Fe catalyst island roughly 10 nm in diameter was frequently observed at the pointed tip of the silicon nanostructure and an interface between the carbon and silicon nanostructures via an Fe catalyst island at the pointed tip of the silicon nanostructure was sometimes observed. The potential of this method for large-scale controlled production of silicon-carbon nanotube heterostructures, without the requirement of a common catalyst for both silicon and carbon1, is explored.


  1. J. Hu, M. Ouyang, P. Yang and C. M. Lieber, "Controlled growth and electrical properties of heterojunctions of carbon nanotubes and silicon nanowires", Nature, Vol. 399, pp. 48-51 (1999)

Abstract in Microsoft Word® format 120,134 bytes

*Corresponding Address:
V. M. Ayres
Dept. of Electrical & Computer Engineering, Michigan State University
Room 2120 Engineering Building, East Lansing, MI 48824 USA
Phone: 517-355-5236 Fax: 517-353-1980


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