Carbon nanofilaments could be formed on silicon oxide substrates over a wide temperature range of 350-1050 degrees C by a thermal chemical vapor deposition system. Using a vacuum-sublimation method, we deposited Fe metal catalyst nanograins on the substrate and carried out carbon nanofilament depositions as a function of the substrate temperature. The diameters of the carbon nanofilaments increased at a higher substrate temperature range. At 350 degrees C, the diameters of carbon nanofilaments were measured to be around 50 nm. At 850 degrees C, however, they seemed to be above 150 nm. Above 850 degrees C, the carbon nanofilaments seemed to be transformed into amorphous carbon. The cause for the variation of the carbon nanofilament diameter as a function of temperature is discussed in association with the surface migration of Fe metal catalyst nanograins and their agglomeration.

Keywords: carbon nanofilaments; thermal chemical vapor deposition; temperature effect