6 research outputs found
Analysis of photon emission induced by light and heavy ions in time-of-flight medium energy ion scattering
No full textWe present a systematic analysis of the photon emission observed due to impact of pulsed keV ion beams in time-of-flight medium energy ion scattering (ToF-MEIS) experiments. Hereby, hydrogen, helium and neon ions served as projectiles and thin gold and titanium nitride films on different substrates were employed as target materials. The present experimental evidence indicates that a significant fraction of the photons has energies of around 10 eV, i.e. on the order of typical valence and conduction band transitions in solids. Furthermore, the scaling properties of the photon emission with respect to several experimental parameters were studied. A dependence of the photon yield on the projectile velocity was observed in all experiments. The photon yield exhibits a dependence on the film thickness and the scattering angle, which can be explained by photon production along the path of the incident ion through the material. Additionally, a strong dependence on the projectile type was found with the photon emission being higher for heavier projectiles. This difference is larger than the respective difference in electronic stopping cross section. The photon yield shows a strong material dependence, and according to a comparison of SiO2 and Si seems to be subject to matrix effects. (C) 2017 Elsevier B.V. All rights reserved.</p
Structural characterization of Pb nanoislands in SiO2/Si interface synthesized by ion implantation through MEIS analysis
No full textIsotopic labeling study of oxygen diffusion in amorphous LaScO3 high-k films on Si(100) and its effects on the electrical characteristics
No full textThe influence of post-deposition oxygen anneals on the properties of amorphous LaScO3 films on Si(100) is reported. The use of an isotopically (O-18(2)) enriched atmosphere allowed to investigate the O-16-O-18 exchange and the oxygen diffusion across the dielectric layer. Such effects are connected to the formation of an interfacial layer. Oxygen annealing leads to nearly ideal capacitance-voltage curves, lower leakage currents and interface trap densities, as well as to kappa-values up to 33 for the LaScO3 films. These results are attributed to the suppression of oxygen-related trap centers and the achievement of a stoichiometric oxygen content
Modelagem classica e Bayesiana : uma evidencia empirica do processo inflacionario brasileiro
No full textTese (doutorado) - Universidade Federal de Santa Catarina. Centro TecnologicoEste trabalho de pesquisa tem por objetivo, em essência, realizar uma investigação empírica sobre o comportamento do processo inflacionário, procurando verificar as relações entre oferta monetária, preços, salários, taxa de juros, taxas de câmbio, dívida federal e uso da capacidade instalada (hiato do produto) no período de janeiro de 1971 a dezembro de 1991, bem como detectar as mudanças estruturais ocorridas e investigar se os choques de oferta influênciam na direção de causalidade entre as variáveis no período amostral analisado, através da utilização das modelagens Clássica e Bayesiana. Para análise de séries temporais também foi proposto um algoritmo de monitoração de dados que permite detectar "outliers" nas séries temporais que podem provocar mudanças na direção de causalidade de variáveis econômicas
Isotopic Labeling Investigation of Oxygen Annealed LaScO3 high-k films Grown on Si(100) by Molecular Beam Deposition
No full textMagnetron sputtering of carbon supersaturated tungsten films – A chemical approach to increase strength
No full textTungsten (W)-based materials attract significant attention due to their superior mechanical properties. Here, we present a chemical approach based on the addition of carbon (C) for increased strength via the combination of three strengthening mechanisms in W thin films. W:C thin films with C concentrations up to ~4 at.% were deposited by magnetron sputtering. All films exhibit a body-centred-cubic structure with strong texture and columnar growth behaviour. X-ray and electron diffraction measurements suggest the formation of supersaturated W:C solid solution phases. The addition of C reduced the average column width from ~133 nm for W to ~20 nm for the film containing ~4 at.% C. The column refinement is explained by a mechanism where C acts as re-nucleation sites. The W film is ~13 GPa hard, while the W:C films achieve a peak hardness of ~24 GPa. The W:C films are ~11 GPa harder than the W film, which is explained by a combination of grain refinement strengthening, solid solution strengthening and increased dislocation density. Additional micropillar compression tests showed that the flow stress increased upon C addition, from ~3.8 to ~8.3 GPa and no brittle fracture was observed
