Microwave plasma-enhanced chemical vapor deposition of carbon nanostructures using biological molecules

Biological molecules are used as catalysts for the growth of carbon nanostructures by microwave plasma-enhanced chemical vapor deposition. Large and small carbon nanotubes are formed perpendicular to the silicon substrate. The dependence of the initial coverage of ferritin molecules on the surface as well as the bias voltage dependence on the structures grown are investigated. The ferritin molecules tend to diffuse and coalesce at high temperatures and high bias voltages, which gives rise. to the large carbon nanotubes with a few tens of nanometers in diameter. The density of the small nanotubes increases with decreasing bias voltage.