1 research outputs found
Catalytic Purification of Directly Written Nanostructured Pt Microelectrodes
In
the majority of cases, nanostructures prepared by focused electron
beam induced deposition employing an organometallic precursor contain
predominantly carbon-based ligand dissociation products. This is unfortunate
with regard to using this high-resolution direct-write approach for
the preparation of nanostructures for various fields, such as mesoscopic
physics, micromagnetism, metaoptical phenomena in the visible spectral
range, or others. Following early attempts of postprocessing Pt-based
structures prepared by focused electron beam induced deposition at
several hundred degrees Celsius in a reactive gas atmosphere, recent
work has focused on developing in situ purification processes by using
a stationary O<sub>2</sub> flux in combination with electron irradiation
to oxidize the carbonaceous component of the deposits. Here we show
that this purification process is driven by the catalytic activity
of Pt and in fact does not rely on the parallel electron irradiation
process to function, if the O<sub>2</sub> exposure is done in a pulsed
fashion. We suggest a multistep cleaning mechanism which results in
pure, nanoporous Pt. By suitably chosen beam parameters, high-resolution
Pt dot and line structures with dimensions below 10 nm can thus be
conveniently obtained. In temperature-dependent resistance measurements,
we find the typical metallic behavior of Pt. In low-temperature magnetoresistance
measurements, we see clear evidence for weak antilocalization effects
and deduce a dephasing length of 234 nm at 1.2 K. We consider this
to be a promising starting point for developing this approach into
a versatile preparation technique for Pt-based mesoscopic structures,
in particular since the purification process can be run in parallel
on different deposits. We furthermore anticipate that our results
will spur further research on purification approaches for nanostructures
prepared by focused electron beam induced deposition containing a
catalytically active metal species such as Pd-, Fe-, or Co-based deposits