Top-Down Heating for Low Substrate Temperature Synthesis of Carbon Nanotubes

A top-down heating method to allow for low-temperature large area synthesis of carbon nanotubes using plasma-enhanced chemical vapour deposition is introduced in this paper. The approach utilizes top-down electromagnetic heating rather than conventional heating from a substrate heater under the electrode. A temperature gradient is created between the Ni catalyst surface and the substrate using a metal thermal control barrier layer, on which carbon nanotubes are grown as a function of the bias voltage, hydrocarbon concentrations and growth conditions. The heat during growth is provided by the plasma or energy coupling to the catalyst via top-down heating, which based on the coupled power density and the cooling of the substrate, in addition to the thermal 'barrier layer' properties will dictate the temperature of the growth surface. This unique approach of top-down heating with suitable cooling schemes, coupled with thermal barriers allows for the low substrate temperature synthesis of carbon nanotubes, scalable to large areas.