Speaker
Alebia Chami
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P1.3016.pdf
Characterization of magnetron sputtering discharges
used for the formation of metallic nanoparticles
A. Chami1, L. Couedel1, T. Acsente2, C. Arnas1
1
Aix-Marseille university, CNRS, Laboratoire PIIM, campus St Jérôme, 13397 Marseille, France
2
National Institute for Laser Plasma and Radiation Physics, PO Box Mg-36, Magurele,
RO 077125, Romania
The aim of our current experiments is to study the formation and transport of metallic
nanoparticles (NPs) in conditions of DC magnetron discharges. Tungsten cathodes were used
as sources of sputtered atoms/clusters, which are the very first NP precursors. The Argon
pressure was varied between 20 to 40 Pa, a pressure range larger than that used for deposition.
A grounded disc was placed 10 cm below the cathode (top of the device). The discharge current
was fixed at 0.3 A or 0.5 A. NPs were collected on substrates placed in the center of the
grounded disc.
In such configuration, the magnetic field lines and strength were measured using a Hall probe.
A cylindrical Langmuir probe allowed establishing a 2D map of the electron density and
temperature between the cathode and the grounded disc. The evolution of these plasma
parameters was correlated to the magnetic geometry and the forces applied to NPs can be
deduced for typical sizes.
The NP sizes were investigated with electron microscopy (SEM, TEM), the atomic structures
and compositions with HR-TEM and EDS mapping. The produced W-NPs have a typical
structure (monocrystal) showing that they have grown by deposition during their transport
across the plasma. The core of these particles exhibits the beta-W crystalline phase. Oxide
shells indicate likely oxidation after the chamber venting. Growth laws have been established
as a function of the argon pressure (20 Pa to 50 Pa) for two discharge currents (0.3, 0.5 A) and
as a function of the plasma duration for a given pressure. These results are discussed as a
function of the discharge geometry as well as the discharge parameters. In a near future, the
laser light scattering technics will be used to correlate the NP transport from the cathode region
towards the substrates.
