Low-temperature growth of vertically aligned carbon nanotubes for field emission

We have investigated a low-temperature growth process of vertically aligned carbon nanotubes on a normal glass plate, which is applicable to the preparation of large-sized field emission devices. The development involves the preheating of a carbon source gas and the use of binary-layered metal catalysts. We have found that the preheating at 700degreesC enhances the reactivity of a carbon source gas of acetylene and contributes to the decomposition of the gas in high efficiency on the surfaces of the catalysts heated even at 450degreesC. For the catalysts, we have examined Fe/Al, Fe/Ti and Co/Ti. It is found that the Al base layer enhances the reaction of Fe but the Ti base layer does not. The combination of Ti base layer with Co instead of Fe is effective for growth of aligned nanotubes at a low temperature. It is also found that the precarbonization of catalysts is effective for Fe related catalysts to enhance their reaction. For Co/Ti catalysts the thickness is an important factor and thinner one is effective. The field emission properties of the low-temperature grown nanotubes have been demonstrated.