  Single-walled carbon nanotubes show promise as nanoscale transistors, for
nanocomputing applications. This use will require appropriate methods for
creating electrical connections between distinct nanotubes, analogous to
welding of metallic wires at larger length scales, but methods for performing
nanoscale chemical welding are not yet sufficiently understood. This study
examined the effect of Ar bombardment on the junction of two crossed
single-walled carbon nanotubes, to understand the value and limitations of this
method for generating connections between nanotubes. A geometric criterion was
used to assess the quality of the junctions formed, with the goal of
identifying the most productive conditions for experimental ion bombardment. In
particular, the effects of nanotube chirality, Ar impact kinetic energy, impact
particle flux and fluence, and annealing temperature were considered. The most
productive bombardment conditions, leading to the most crosslinking of the
tubes with the smallest loss of graphitic (i.e. conductive) character, were
found to be at relatively mild impact energies (100 eV), with low flux and high
temperature (3000 K) annealing. Particularly noteworthy for experimental
application, a high junction quality is maintained for a relatively broad range
of fluences, from 3E19 m^-2 to at least 1.0E20 m^-2.
