Carbon Nanotube Growth from Nanoscale Clusters Formed by Ion Implantation

We have demonstrated that iron ions implanted into silicon dioxide thin films form nanoscale clusters which can act as catalyst for carbon nanotube growth. We have implanted iron ions with an energy of 60 keV and three different doses (1014, 1015, and 1016 cm-2) into silicon dioxide thin films thermally grown on silicon substrates. We then used chemical vapor deposition (CVD) to grow carbon nanotubes on these ion implanted substrates with methane as the precursor gas. We studied the effect of ion implantation dose on the structural properties of the nanoscale clusters, as well as the carbon nanotubes nucleated from these clusters. The nanoscale clusters and grown nanotubes were characterized by Atomic Force Microscopy and Raman spectroscopy. The electrical characteristics of the as-grown nanotubes were also characterized. We found that growth of low density, horizontal, and small diameter carbon nanotubes on silicon dioxide is possible using this nucleation technique.