Large arrays of well-aligned carbon nanotubes on glass, silicon, nickel, platinum, etc. have been successfully synthesized by plasma enhanced chemical vapor deposition at temperatures below 500 °C. Either a uniform layer of nickel made by magnetron sputtering or patterns of nickel dots made by e-beam lithography and e-beam evaporation or thermal evaporation was used as the catalyst. Acetylene and ammonia gases were used as the carbon source and dilution gas. Ammonia was also found to act as catalyst. Without ammonia, there was no growth of carbon nanotubes at that low temperature. The diameters of the carbon nanotubes range from a few nanometers to a few hundred nanometers depending on the catalytic nickel size. The length is in a range of a few thousand angstroms to a few hundred micrometers depending on the growth time. In the case of uniform nickel layer used for catalyst, the site density of carbon nanotubes range between 109 to 1012/cm2 depending on the diameters of the nanotubes. Whereas in the case...