Executive Summary Final - the Center for Nanoscale Science - an ...

IRG 3: Transport in nanowires
also makes it possible to carry out tunneling measurements to probe the nature of the
superconducting gap of a NW exhibiting proximity and anti-proximity behaviors.
The IRG has a continuing effort in synthesizing NWs with diameters around and below 10 nm.
Au wires with diameters as thin as 6 nm have been reliably grown by electro-deposition.
However, when these wires are ‘harvested’ they tend to coalesce into bundles. We have begun an
effort to apply a thin (few Å) silica layer to the pore walls of the porous membrane prior to
electro-deposition of the metallic wires. This procedure has been successfully used in Mallouk’s
lab in growing Au wires of ~100 nm inside silica ‘nanotubes’, a configuration which should help
suppress bundling. We are now employing this technique to grow Au and Bi wires down to ~10
nm.
IRG 4 has pioneered the growth of 1-D semiconductors inside hollow optical fibers by means of
high-pressure fluid deposition. The well-defined hollow pores can be under 100 nm across and
the length can be longer many centimeters, a unique capability. IRG 3 has identified this system
as an opportunity to grow Sn and other superconducting NWs in unprecedented geometries, and
we have begun a collaboration with IRG 4 with this goal. The availability of these NWs will
allow us to push the study of (quasi) 1-D superconductivity from the micron to the centimeter
length scale.