Control of carbon capping for regrowth of aligned carbon nanotubes.

The regrowth of carbon nanotubes (CNTs) in a second growth stage after a first growth stage has been completely stopped has been found to be strongly related to the carbon capping present on their catalyst particles. It is shown that the undesirable carbon capping can be prevented from forming or removed and the nanotube growth can be rejuvenated by either control of plasma processing conditions during chemical vapor deposition or by inserting a room-temperature sputter etching process. The ability to cause sequential growth stages to take place in different directions makes it possible for us to clearly compare the occurrence and extent of CNT regrowth. Such a CNT regrowth process and understanding of controlling parameters can enable the creation of new nanowire configurations that could potentially be used for applications such as sharply bending nanointerconnections, nanosprings, bent AFM nanoprobes, or nanobarcodes.