Well-defined multiwalled
carbon nanotube structures are generated
on stainless steel AISI 304 (EN AW 1.4301) by chemical vapor deposition.
Pulsed laser-induced dewetting (PLiD) of the surface, by 532 nm nanosecond
laser pulses, is utilized for the preparation of metal oxide nanoparticle
fields with a defined particle number per area. The reduction of the
precursor particles is achieved in an Ar/H2 (10% H2) atmosphere at 750 °C, thereby generating catalytic
nanoparticles (c-NPs) for carbon nanotube (CNT) growth. Ethylene is
used as a precursor gas for CNT growth. CNT lengths and morphology
are directly related to the c-NP aerial density, which is dependent
on the number of dewetting cycles during the PLiD process. Within
a narrow window of c-NP per area, vertically aligned carbon nanotubes
of great lengths are obtained. For more intense laser treatments,
three-dimensional dewetting occurs and results in the formation of
cauliflower-like structures. The laser process enables the creation
of all kinds of CNT morphologies nearby on the microscale.
Laser-induced periodic surface structures (LIPSS) provide an elegant solution for the generation of highly ordered periodic patterns on the surface of solids. In this study, LIPSS are utilized for the formation of periodic platinum nanowire arrays. In a process based on laser-stimulated self-organization, platinum thin films, sputter-deposited onto silicon, are transformed into nanowire arrays with an average periodicity of 538 nm. The width of the platinum nanowires is adjustable in a range from 20 nm to 250 nm by simply adjusting the thickness of the initial platinum thin films in a range from 0.3 nm to 4.3 nm. With increasing width, platinum nanowires show a rising tendency to sink into the surface of the silicon wafer, thus indicating alloying between platinum and silicon upon LIPSS-formation by a nanosecond-pulsed laser. The Pt/silicon wires may be etched away, leaving a complementary nanostructure in the silicon surface.
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