Obtención y caracterización de contactos Schottky al-Asga

Tesi de Llicenciatura per a l'obtenció del Grau de Física. Universitat de Barcelona. Director: Morenza Gil, José Luis. Any: 1981

Evaluación de las propiedades tribológicas y mecánicas de recubrimientos de CrC depositados por pulverización catódica magnetrón R.F.

Este artículo presenta los resultados obtenidos con el depósito de una serie de recubrimientos de CrC mediante pulverización catódica por magnetrón r.f., la cual presentó contenidos de carbono en el rango de 2558 % acorde a los análisis EDS. Los valores de dureza de estos recubrimientos estuvieron entre 15 y 24 GPa, hallándose los valores de mayor dureza en las muestras con contenido de carbono en el rango de 3953 %. Se encontró una correlación entre el contenido de carbono y los valores de los coeficientes de fricción, los cuales están en el rango de 0,70 a 0,15, obteniendo estos últimos valores para recubrimientos con exceso de carbono. El comportamiento al desgaste bajo pruebas de deslizamiento en seco mostró también una marcada dependencia con el contenido de carbono. Los mejores resultados de desgaste fueron obtenidos para los recubrimientos con el más alto contenido de carbono

Chemical and mechanical stability of air annealed cathodic arc evaporated CrAlON coatings

This study reports the synthesis and characterization of ternary Cr-Al-O and quaternary Cr-Al-O-N coatings deposited by cathodic arc physical vapour deposition, for various nitrogen and oxygen mass flow ratios during the growth process. The composition, microstructure, indentation hardness and modulus of the films have been characterized by scanning electron microscopy, electron probe micro-analysis, X-ray diffraction, and nanoindentation techniques. The evolution of the microstructure and mechanical properties of the coatings after ambient air annealing from 800 °C up to 1100 °C have been investigated. As the oxygen to nitrogen mass flow increases, the as-deposited coatings exhibit lower hardness, higher roughness, lower crystallinity and a more marked columnar structure. At oxygen to nitrogen mass flow ratios bigger than 10/90, the coatings exhibit a stoichiometry of the type (CrAl)2+εO3−ε. Only the coatings with an oxygen to nitrogen mass flow ratio smaller than 10/90 retained nitrogen in their compositions. In all cases, the coatings developed a cubic fcc lattice structure. After annealing at 1100 °C the resulting microstructure showed a clear dependency upon the initial composition of the films. The evolution of the microstructure during the high temperature tests, as well as the analysis of the nanoindentation hardness, composition and thickness also provided valuable information about the combined effects of the thermal stability and the oxidation of the deposited coatings

Ion assisted deposition of thin films by substrate tuned radio frequency magnetron sputtering

The substrate tuning technique was applied to a radio frequency magnetron sputtering system to obtain a variable substrate bias without an additional source. The dependence of the substrate bias on the value of the external impedance was studied for different values of chamber pressure, gas composition and rf input power. A qualitative explanation of the results is given, based on a simple model, and the role of the stray capacitance is clearly disclosed. Langmuir probe measurements show that this system allows independent control of the ion flux and the ion energy bombarding the growing film. For an argon flow rate of 2.8 sccm and a radio frequency power of 300 W (intermediate values of the range studied) the ion flux incident on the substrate was 1.3 X 1020-m-2-s-1. The maximum ion energy available in these conditions can be varied in the range 30-150 eV. As a practical application of the technique, BN thin films were deposited under different ion bombardment conditions. An ion energy threshold of about 80 eV was found, below which only the hexagonal phase was present in the films, while for higher energies both hexagonal and cubic phase were present. A cubic content of about 60% was found for an ion energy of 120 V

Ion assisted deposition of thin films by substrate tuned radio frequency magnetron sputtering

The substrate tuning technique was applied to a radio frequency magnetron sputtering system to obtain a variable substrate bias without an additional source. The dependence of the substrate bias on the value of the external impedance was studied for different values of chamber pressure, gas composition and rf input power. A qualitative explanation of the results is given, based on a simple model, and the role of the stray capacitance is clearly disclosed. Langmuir probe measurements show that this system allows independent control of the ion flux and the ion energy bombarding the growing film. For an argon flow rate of 2.8 sccm and a radio frequency power of 300 W (intermediate values of the range studied) the ion flux incident on the substrate was 1.3 X 1020-m-2-s-1. The maximum ion energy available in these conditions can be varied in the range 30-150 eV. As a practical application of the technique, BN thin films were deposited under different ion bombardment conditions. An ion energy threshold of about 80 eV was found, below which only the hexagonal phase was present in the films, while for higher energies both hexagonal and cubic phase were present. A cubic content of about 60% was found for an ion energy of 120 V

Evaluación de las propiedades tribológicas y mecánicas de recubrimientos de CrC depositados por pulverización catódica magnetrón R.F.

Este artículo presenta los resultados obtenidos con el depósito de una serie de recubrimientos de CrC mediante pulverización catódica por magnetrón r.f., la cual presentó contenidos de carbono en el rango de 2558 % acorde a los análisis EDS. Los valores de dureza de estos recubrimientos estuvieron entre 15 y 24 GPa, hallándose los valores de mayor dureza en las muestras con contenido de carbono en el rango de 3953 %. Se encontró una correlación entre el contenido de carbono y los valores de los coeficientes de fricción, los cuales están en el rango de 0,70 a 0,15, obteniendo estos últimos valores para recubrimientos con exceso de carbono. El comportamiento al desgaste bajo pruebas de deslizamiento en seco mostró también una marcada dependencia con el contenido de carbono. Los mejores resultados de desgaste fueron obtenidos para los recubrimientos con el más alto contenido de carbono

Evaluación de las propiedades tribológicas y mecánicas de recubrimientos DE CrC depositados por pulverización catódica magnetrón R.F.

This paper presents the results obtained with a series of CrC coatings deposited by means of r.f magnetron sputtering, which presented carbon contents in the range between 2558% as it is shown by EDS measurements. Hardness values of these coatings were between 15 and 24GPa, being the hardest values in the samples with carbon content in the 3953% range. A correlation has been found between carbon content and friction coefficient values which are in the 0,70 to 0,15 range, obtaining these last values for coatings with carbon excess. Wear behavior under dry sliding tests showed also a marked dependence with carbon content. The best results of wear were obtained for the highest carbon content coatingsEste artículo presenta los resultados obtenidos con el depósito de una serie de recubrimientos de CrC mediante pulverización catódica por magnetrón r.f., la cual presentó contenidos de carbono en el rango de 2558% acorde a los análisis EDS. Los valores de dureza de estos recubrimientos estuvieron entre 15 y 24 GPa, hallándose los valores de mayor dureza en las muestras con contenido de carbono en el rango de 3953%. Se encontró una correlación entre el contenido de carbono y los valores de los coeficientes de fricción, los cuales están en el rango de 0,70 a 0,15, obteniendo estos últimos valores para recubrimientos con exceso de carbono. El comportamiento al desgaste bajo pruebas de deslizamiento en seco mostró también una marcada dependencia con el contenido de carbono. Los mejores resultados de desgaste fueron obtenidos para los recubrimientos con el más alto contenido de carbono

Rheotaxial growth of CuInSe2 thin films

CuInSe2 thin films were deposited onto glass and liquid¿indium¿coated glass substrates by coevaporation of copper, indium, and selenium. The morphology, composition, and crystalline properties have been studied in relation to the deposition process parameters. The deposition rate and the grain size are higher in films grown on liquid indium than on glass and depend on the indium film thickness. Films grown on indium do not show the same crystalline phases of films grown on glass, and in order to obtain films free of spurious phases the Cu fluxes must be increased

Magnetic studies of Fe-Y compositionally modulated thin films

Compositionally modulated thin films of Y/Fe have been studied by using SQUID magnetometry. Samples were grown by electron‐beam evaporation onto Kapton substrates. In the low applied field regime, the samples show irreversible behavior when they are submitted to ZFC‐FC magnetization processes, increasing the irreversibility zone as the thickness of the Fe layers increases. In the high applied magnetic field regime (H≥10 000 Oe), samples show ferromagnetic behavior. The temperature dependence of the saturation magnetization has been studied, and it was found that both spin‐wave excitations and Stoner excitations occur at temperatures higher than 40 K, and a marked deviation from the T3/2 law was noted below 30 K