Uniform patterned growth of carbon nanotubes without surface carbon

In order to utilize the unique properties of carbon nanotubes in microelectronic devices, it is necessary to develop a technology which enables high yield, uniform, and preferential growth of perfectly aligned nanotubes. We demonstrate such a technology by using plasma-enhanced chemical-vapor deposition ~PECVD! of carbon nanotubes. By patterning the nickel catalyst, we have deposited uniform arrays of nanotubes and single free-standing aligned nanotubes at precise locations. In the PECVD process, however, detrimental amorphous carbon (a-C) is also deposited over regions of the substrate surface where the catalyst is absent. Here, we show, using depth-resolved Auger electron spectroscopy, that by employing a suitable deposition ~acetylene, C2H2! to etching ~ammonia, NH3! gas ratio, it is possible to obtain nanotube growth without the presence of a-C on the substrate surface. © 2001 American Institute of Physics. @DOI: 10.1063/1.1400085#