Manuel García-Méndez

STRUCTURAL PROPERTIES OF AlN FILMS WITH OXYGEN CONTENT DEPOSITED BY REACTIVE MAGNETRON SPUTTERING: XRD AND XPS CHARACTERIZATION

A set of aluminium nitride (AlN) and oxidized AlN (AlNO) thin films were grown with the technique of direct current (dc) reactive magnetron sputtering. The main purpose of this investigation is to explore the influence of the oxygen on the structural properties of AlN and AlNO films. The crystalline properties and chemical identification of phases were studied by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), respectively. Electrical properties were analyzed from I-V measurements. It was found that films crystallized under the AlN wurzite structure and presented a polycrystalline preferential growth along [0001] direction, perpendicular to substrate. Small amounts of secondary aluminium oxide phases were detected too. The oxide phases can induce defects, which can alter crystallinity of films.

Classical Plasmonics: Wave Propagation Control at Subwavelength Scale

In this paper, surface plasmons polariton propagation and manipulation is reviewed in the context of experiments and modeling of optical images. We focus our attention in the interaction of surface plasmon polaritons with arrays of micro-scatereres and nanofabricated structures. Numerical simulations and experimental results of different plasmonic devices are presented. Plasmonic beam manipulation opens up numerous possibilities for application in biosensing, nanophotonics, and in general in the area of surface optics properties.

Ce(1-x)MXO2, {M=Ru, In} Solid Solutions as Novel Gas Sensors for CO Detection

In the present work, the study of semiconducting Ce(1-x)MXO2 (M=Ru, In) solid-solutions nanostructures with application to gas sensors is addressed. Nanostructured powers were prepared by means of the sol-gel route. The electrical resistance of obtained materials under different conditions of time, concentration and temperature in CO presence was tested. These systems were characterized using x-ray diffraction, SEM microscopy and surface area measurements. The solid solutions demonstrated good sensorial response at low temperatures, as well as fast response as a function of time. Our results show that these novel materials can be potentially applied as gas sensors.

Chemical Characterization of DC-Sputtered In2O3 Films with a Top SnO2 Layer

In2O3 thin films with a top layer of SnO2 were deposited onto glass substrates by DC reactive-magnetron sputtering. After deposition, In2O3/SnO2 samples were annealed in vacuum at 400oC. Structural, optical, and chemical composition was investigated by X-ray diffraction, UV-Vis spectroscopy and XPS, respectively. X-ray data showed that films grow polycrystalline, where indium oxide crystallized in cubic as the main phase, with a preferential growth at the [0002] direction and lattice parameter of 10.11 Å. Signals of rhombohedral phase were also detected. XPS depth profiles show that tin coexists in Sn2+ and Sn4+, while indium maintains the In2O3 stoichiometry. Binding energy of Sn4+ bound to oxygen was detected at 468 eV while In2+ bound to oxygen at 444.7 eV. Nor tertiary compounds were detected at the In2O3/SnO2 interface, neither In or Sn in metallic state.

Developing novel gas sensors for NO2 detection based on Ce(1-x)MXO2, {M = Ru, In} solid solutions

CeO2, Ce(1-x)MXO2, {M = Ru, In} compounds with sensing properties were fabricated using the sol–gel route. The main purpose was to compare the efficiency of CeO2 vs. Ce(1-x)MXO2 doped compounds as gas sensors for NO2 detection. Characterization was performed by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and surface area determination (BET). Measurements of electrical resistance under different conditions of time, concentration and temperature in the presence of NO2 were carried out. Ruthenium inclusion increased the CeO2 sensor response in a great extent, gas response (S) = 1.8 for CeO2 vs. gas response (S) = 350 for Ce0.95Ru0.05O2 and gas response (S) = 35 for Ce0.95In0.05O2. This behavior is reported by the first time. Our results demonstrate that ruthenium or indium inclusion has been beneficial for CeO2. Conclusively the materials herein described could be applied as NO2 gas sensors.

DEPOSITION OF AlN AND OXIDIZED AlN THIN-FILMS BY REACTIVE SPUTTERING: CORRELATION BETWEEN FILM GROWTH AND DEPOSITION PARAMETERS

A set of AlN films were deposited by reactive direct current (DC) magnetron sputtering. Films were analyzed with X-ray diffraction and Auger Electron Spectroscopy (AES). There is a correlation between deposition parameters and crystal growth. Depending on the deposition parameters, films can present a hexagonal wurzite (P6mm) or cubic zinc-blend (Fm3m) microstructure. Oxygen appears to induce on films a degree of amorphous growth and a distortion of the lattice parameters. For the film with cubic microstructure, AES transitions detected near the surface level at 56 eV and 66 eV were attributed to aluminum-oxide (AlxOy), AlN, and metallic Al.

Synthesis of Transparent Conductive Thin Films of In2O3 and SnO2 by DC Magnetron Sputtering

Study of optical and microestructural properties in In2O3 and SnO2 multilayer thin films synthesis by DC magnetron sputtering characterized with SEM, X-RD and four point probe resistivity where is possible appreciate an enhancement in conductivity.