We developed a system to deliver a large flux of O atoms for the removal of hydrogenated carbon films from surfaces in remote areas of tokamaks with carbon divertors. The oxygen plasma is generated via electrodeless radiofrequency discharge in a discharge chamber connected to a remote chamber by a 2 m long complex shaped glass tube 4 cm in diameter. The density of O atoms in the remote chamber was measured with a nickel catalytic probe and its variation with discharge power obtained. Experiments were performed at sample temperatures up to 600 K and etching rates up to 50 nm/s were obtained.
COBISS.SI-ID: 25950503
Surface/interface roughness has a significant influence on the shape of the depth profile measured by any depth profiling technique. Such an influence is particularly significant for thin delta layers and at sharp interfaces of single- and multilayers. In the mixing-roughness-information MRI model for quantification of measured depth profiles, the influence of roughness is usually taken into account by a Gaussian height distribution function. Our results show that a realistic asymmetrical non-Gaussian function has to be taken into account if high accuracy in quantification of sputter depth profiles is required. Application of an asymmetrical height distribution function in the MRI model yields an excellent fit for the measured AES depth profiling data of a polycrystalline Al film.
COBISS.SI-ID: 27406631
We reported on the chemical synthesis of the arrays of silicon oxide nano-dots and their self-organization on the surface via physical processes triggered by surface charges. The method based on chemically active oxygen plasma leads to the rearrangement of nanostructures and eventually to the formation of groups of nano-dots. This behaviour is explained in terms of the effect of electric field on the kinetics of surface processes. The direct measurements of the electric charges on the surface demonstrate that the charge correlates with the density and arrangement of nano-dots within the array.
COBISS.SI-ID: 26571303
Our program group member Dr Matjaž Panjan spent his postdoc at the prestigious Lawrence Berkeley National Laboratory (USA), supported by the Fulbright fellowship. Together with the Berkley coworkers they proposed a model for ion transport in high-power pulsed magnetron sputtering, which was published in Applied Physics Letters. The model is based on the discovery of inhomogeneous plasma structures, called the ionization zones; in the magnetron plasma they rotate in the direction E×B. In this model they proposed that within the ionization zones the electron and ion densities are spatially separated and thus cause the formation of an electric field in azimuthal direction. This electric field rotates together with the zones. The ions are mainly formed within the ionization zones therefore they acquire the kinetic energy of the rotating electric field, which accelerates them up to the energy of 100 eV or more.
COBISS.SI-ID: 27099687
From a large number of growth defect density measurements on samples from industrial production batches, we performed statistical analysis in order to evaluate the influence of deposition parameters on the defect surface density. We analyzed various PVD hard coatings (TiN, TiAlN, CrN, TiAlN/a-CN, nanostructured AlTiN/TiN and TiAlSiN/TiSiN/TiAlN layers) prepared by different PVD deposition techniques (thermionic arc evaporation, magnetron sputtering) at various deposition conditions. We found that the defect density on various samples in the same batch scatters a lot. There can also be a substantial difference on the two faces of the same sample. This suggests that the formation of growth defects is sporadic and spatially localized. The defect density depends on sample position, deposition time, type of coating material, and batching material. The influence of steel inclusions on coating growth was also analyzed. In order to understand the effects of different inclusions and other irregularities the substrate surface morphology was followed from the cleaning to ion etching and deposition. Shallow craters and voids were observed at positions of MnS inclusions, while the growth of TiAlN/CrN nanolayer coating on SiO2 inclusions was coherent.
COBISS.SI-ID: 27288615