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An inductively coupled SF6/O2 plasma is used to form a columnar microstructure (CMS) on silicon samples cooled at very low temperature (∼ −100 °C). The formation of this CMS is studied as a function of bias voltage, temperature, RF power and gas pressure. The characteristic mean diameter and mean height of the microstructure are evaluated by image processing tools from SEM micrographs. A crystallographic effect is also observed at very low temperature, which induces a needle-shaped structure. A physical mechanism is proposed to explain the formation of this CMS.

Platinum is deposited into porous carbon materials relevant for fuel cell electrodes using plasma sputtering techniques. The resulting platinum concentration profile extends up to 2 µm into the porous carbon and is well fitted by a generalized stretched Gaussian function, which displays the non thermal nature of the penetration process. Platinum deposits are observed to grow as clusters. On the outermost carbon particles, platinum nano-cluster sizes of 3.5 nm have been measured. In tests using actual PEM fuel cells, current densities as high as 1000 mA.cm −2 have been obtained at 400 mV with 25 cm 2 plasma electrodes. This compares favourably with commercially available electrodes but the present electrodes have a platinum density 4.5 times lower and hence can be considered to be significantly more efficient.

Constant flux atom deposition into a porous medium is shown to generate a dense overlayer and a diffusion profile. Scaling analysis shows that the overlayer acts as a dynamic control for atomic diffusion in the porous substrate. This is modeled by generalizing the porous diffusion equation with a time-dependent diffusion coefficient equivalent to a nonlinear rescaling of time.

Ultra-low Pt content PEMFC electrodes have been manufactured using magnetron cosputtering of carbon and platinum on a commercial E-Tek ® uncatalyzed gas diffusion layer in plasma fuel cell deposition devices. Pt loadings of 0.16 and 0.01 mg cm -2 have been realized.The Pt catalyst is dispersed as small clusters with size less than 2 nm over a depth of 500 nm.PEMFC test with symmetric electrodes loaded with 10 µg cm -2 led to maximum reproducible power densities as high as 0.4 W cm -2 and 0.17 W cm -2 with Nafion ® 212 and Nafion ® 115 membranes, respectively.

Plasma‐surface interactions are in general highly complex due to the interplay of many concurrent processes. Molecular dynamics simulations provide insight in some of these processes, subject to the accessible time and length scales, and the availability of suitable force fields. In this introductory tutorial‐style review, we aim to describe the current capabilities and limitations of molecular dynamics simulations in this field, restricting ourselves to low‐temperature non‐thermal plasmas. Attention is paid to the simulation of the various fundamental processes occurring, including sputtering, etching, implantation, and deposition, as well as to what extent the basic plasma components can be accounted for, including ground state and excited species, electric fields, ions, photons, and electrons. A number of examples is provided, giving an bird's eye overview of the current state of the field.

A parametric study of single-crystal silicon roughness induced by an SF6 plasma has been carried out by means of atomic force microscopy. An helicon source (also called resonant inductive plasma etcher) has been used to study the relation between plasma parameters and subsequent surface damage. The surface damage has been examined in terms of height roughness analysis and in terms of spatial (lateral) extent of the surface roughness. The central result is that roughness scales with the ratio of the ion flux over the reactive neutral flux (J+/JF), showing the combined role of both ionic and neutral species. At low ion flux, the neutrals smooth the surface, while at higher ion flux, they propagate the ion-induced defects, allowing the roughness to be enhanced. Influences of other parameters such as exposure duration, ion energy, or substrate temperature have also been quantified. It is shown that the roughness growth is well described by an empirical law: rms∝(1/√E)(J+/JF)ηtβ, with η≊0.45 and β≊1 (rms is the root mean square of the roughness). In other respects, we analyze the data with a Fourier transform analysis. The main advantage is to minimize noise and to separate the magnitude of the roughness, the lateral correlation length on which the roughness is growing, and the behavior of short and long range roughness. The results are identical to the rms analysis, especially, the above scaling law. The time evolution of the lateral correlation length follows a scaling law (which is not accessible by means of the rms) leading to a fractal dimension of 2.67. Also is observed a variation of the short range roughness as a function of the substrate bias voltage. Consequence for further scaling down of integrated circuits is called to mind.

High entropy alloys (HEAs), containing five to thirteen metallic elements, with a concentration in the range of 5 to 35 % for each element, exhibit very interesting properties (mechanical, tribological, formability, magnetism...). Their high mixing entropy promotes the formation of simple solid solutions with amorphous or nanocrystallized structure. Bulk pieces of these alloys are known to be stable at relatively high temperature (until 800°C). We study the stability of AlCoCrCuFeNi thin film at temperatures in the range 110 -810 °C. HEA thin films are deposited by magnetron sputtering of mosaic targets. In-situ X-ray diffraction performed during annealing evidences damages of the film above 510°C depending on the initial structure (or chemical composition) of the as-deposited HEA. Energy Dispersive Spectroscopy (EDS) and Scanning Electron Microscopy (SEM) analysis carried out before and after annealing on both studied samples, show that partial evaporation of the thin film, crystalline phase transformation and chemical reaction with the substrate may take place during annealing.