Abstract The physical properties of amorphous indium zinc oxynitride (a-IZON) thin films, which were deposited at room temperature by reactive RF magnetron sputtering, were investigated. The results of the investigations indicated that the a-IZON films possessed excellent qualities: high transparency with a very low resistivity from 10 - 3 Ω ⋅cm to 10 - 4 Ω ⋅cm, while the carrier concentration showed values over 10 20 cm - 3 with mobility between 10 and 21 cm 2 ⋅V - 1 ⋅s - 1. The incorporated nitrogen reduces the typical crystallization of IZO and favors the deposition of transparent thin films. These results show that the IZON is an ideal amorphous material for applications in transparent and flexible optoelectronic devices.

Abstract The effect of Li co-doping on the blue luminescence of Eu2+ doped (La-Al)2 O3 phosphors and its incorporation into poly (methyl methacrylate) PMMA films are reported. The phosphors were synthesized by a simple two-step process in which the (La-Al)2 O3 powders were obtained by an evaporation method, and the subsequent co-doping with Li+ and Eu2+ were made through a solid state reaction in a reductive atmosphere at 1250°C. The incorporation of those phosphors into PMMA matrix and the synthesis of films with thicknesses between 6 and 12 μm was made by drop-casting. The characteristic blue broad band emission centered at 440 nm associated with the 4f65d1→4F7 transition of Eu2+ ions (CIE coordinates 0.6731, 0.3343) was observed when these powders were excited with 297 nm light. These luminescence intensity was enhanced when Li+ was incorporated as co-dopant up to 320% with respect to those phosphors without Lithium. The luminescent characteristics of these phosphors were preserved when they were embedded into the PMMA films.

Abstract In this work, it is shown the feasibility for obtaining silver nanoparticles by ultrasonic spray pyrolysis and their simultaneous incorporation during deposition of thin layers of aluminum oxide to get a Cermet coating of Al2O3-Ag. The synthesis of these Cermets was achieved on the basis of both the simultaneous pyrolysis of silver nitrate and aluminum acetylacetonate on different substrates: Quartz, glass, crystalline silicon (c-Si), and titanium at temperatures of 500, 550 and 600°C. The structural properties of the Cermets were studied by Scanning Electron Microscopy, Atomic Force Microscopy and X-ray diffraction. For the optical properties, UV-vis spectroscopy was used to obtain the optical Absorbance of the Cermets, while the Reflectance was obtained by UV-vis-IR spectroscopy measurements. UV-Vis spectroscopy showed that the intensity of the absorption peak (plasmon) was limited to the concentration of silver nitrate, and it shifted toward shorter wavelengths with the decrease in the size of the Ag nanoparticles inside the Cermets. The plasmon position of Ag nanoparticles in the different samples was found to be centered at 504 nm, 506 nm, 497 nm and 475 nm for samples deposited with 0.1 mol, 0.05 mol, 0.02 mol, and 0.01 mol of Ag(NO3), respectively. The shape of the Ag nanoparticles was approximately spherical, ranging from 4 nm to 35 nm, and their concentration was proportional to the concentration of Ag(NO3) included in the spray solution. By means of the UV-Vis Spectroscopy-IR and FT-IR, in the best of cases, a solar absorptance of 0.83 and an infrared thermal emittance of 0.14, for a sample of Al2O3-Ag prepared with 0.1 mol of Ag(NO3) in the precursor solution, were obtained.

Dysprosium and Lithium-activated yttrium oxide phosphor was synthesized at 1100 °C by ultrasonic spray pyrolysis (USP) using DI water as solvent and metal chlorides as precursors. The characteristic emission peaks of Dy3+ due to the transitions 4F9/2 to 6H15/2 at 483 nm, 4F9/2 to 6H13/2 at 573 nm, 4F9/2 to 6H11/2; at 667 nm and 4F9/2 to 6H9/2 at 766 nm were observed. Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) measurements were carried out to understand surface morphological features and the particle size of the phosphor. The uniformity of phase of Dy3+ _Li+ doped Y2O3 phosphors was checked by X-ray diffraction (XRD) technique. The phosphors form clusters that were found to be ∼1 μm in size, however, particles that form these clusters have sizes between 40 and 120 nm.

Abstract: Different emission intensities presented in aluminum oxide phosphors corresponding to different concentrations of doping performed with terbium are analyzed. The phosphors were synthesized by the evaporation technique and were characterized by photo and cathodoluminescence, x-ray diffraction, and EDS techniques for different incorporation percentages of terbium as dopant; they show characteristic transitions in 494, 543, 587 and 622 nm, corresponding to 5D 4 → 7F 6, 5D 4 → 7F 5, 5D 4 → 7F 4 and 5D 4 → 7F 3, respectively when they are excited with λ e x c = 380 nm wavelength at room temperature. The results of XRD show the presence of α-Al 2O 3 phases with peaks located at 2 θ = 25.78, 35.34, 37.96, 43.56, 45.8, 52.74, 57.7, 61.5, 66.74, 68.44, 77.12 and 80.94, and the δ-Al 2O 3 phase 2 θ = 32.82, 45.8, 61.36 and 66.74. These compounds were heat treated for two hours at 1100 ∘ C. EDS analyzes indicate that these compounds have close to 60% oxygen around of 40% aluminum in the presence of terbium as dopant which indicates a stoichiometry close to the expected one for alumina.

Polystyrene (PS) films doped with blue, yellow and red organic pigments have been deposited on glass and on commercial LED chips by spray pyrolysis using recycled PS as precursor, at deposition rates between 100 and 200 Å/s. Doped films have roughness between 100 and 2500 Å depending on the kind of pigment used; the surface morphology shows that the organic pigments incorporate into the polystyrene host forming globular particles of about 2 μm in diameter. The organic pigments used have luminescent emissions peaked at 440, 509 and 590 nm. The introduction of the proper combination of pigments on the PS film deposited on the LED chips renders a white light emission with (0.29, 0.37) and (0.30, 0.33) CIE (Commission international de l' eclairage) color coordinates. It was determined that the exposure to violet light degrades the luminescent characteristics, however, blue light is not energetic enough to cause a degradation of the luminescent layer over similar period of time.

(ZnO)X-(CdO)1-X thin films were deposited on glass substrates at 300°C and 400°C by ultrasonic spray pyrolysis with compositions ranging from CdO to ZnO. The electrical properties were obtained by impedance spectroscopy and Hall Effect measurements. Scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction, were used to study the structural characteristics of the films. Ellipsometry, in addition, was used to confirm the structural characteristics. The films as deposited resulted mainly polycrystalline and dense, depending on the substrate temperature and on their relative composition. All the films showed n-type conductivity and the films with intermediate compositions resulted in a mixture of both phases; CdO and ZnO. Hall Effect measurements showed that the highest conductivity of CdO was close to 1x10³ (Ω-cm)-1, the highest value obtained for CdO, without doping. Impedance spectroscopy confirmed the Hall Effect results, showing that the highly conducting character of CdO influenced dramatically the conductivity of the (ZnO)X-(CdO)1-X films. In addition, depending on the substrate temperature and on the relative composition of the films, both, the bulk or grains, as well as the grain boundaries properties limit the conductivity in them.

Películas delgadas de (ZnO)x(CdO)1_x fueron depositadas sobre sustratos de vidrio a 300°C y 400°C por rocío pirolítico ultrasónico con composiciones entre CdO y ZnO. Las propiedades eléctricas fueron determinadas a través de medidas de espectroscopia de impedancia y Efecto Hall. Microscopía electrónica de barrido, espectroscopia por dispersión de energía y difracción de rayos X fueron utilizadas para determinar las características estructurales de las películas. Elipsometría fue empleada para confirmar las características estructurales. Las películas, tal y como son depositadas resultaron policristalinas y densas, dependiendo de la temperatura del sustrato y de la composición relativa de ellas. Todas las películas mostraron una conductividad de tipo n y las películas con concentraciones intermedias resultaron con una mezcla de ambas fases; CdO y ZnO. Las mediciones de Efecto Hall mostraron que la más alta conductividad de las películas de CdO fue cercano a 1 x 10³ (Ω-cm)-1, valor más alto obtenido para CdO sin dopante. Las medidas de espectroscopia de impedancia confirmaron los resultados obtenidos por Efecto Hall, y mostraron además que el alto carácter conductor de las películas de CdO influye de manera importante en la conductividad de las películas de (ZnO)X-(CdO)1-X. Además, dependiendo de la temperatura del sustrato y de la composición relativa de las películas ambos, los granos (o el bulto), así como las fronteras de grano, limitan la conductividad en ellas.

By means of the ultrasonic spray pyrolysis technique, trivalent terbium and europium doped hafnium oxide coatings were synthesized. These coatings are non-crystalline at substrate temperatures lower than 350°C; for higher substrate temperatures the films are polycrystalline presenting the HfO2 monoclinic phase. The cathodoluminescence spectra for these films were studied as a function of the substrate temperature and the doping concentration. Samples excited with electron beam showed visible emission bands, associated to the electronic transitions of the trivalent europium and terbium ions. As the substrate temperatures are increased, an increment of the cathodoluminescence emission intensity was detected. In addition, a concentration quenching of the cathodoluminescence intensity was observed. Also, the chemical compositions of the deposited coatings and the characteristics of their surface morphologies are shown.

Mediante la técnica de rocío pirolítico ultrasónico, se depositaron películas de óxido de hafnio activadas ópticamente con terbio y europio trivalentes. El material depositado muestra características amorfas cuando se deposita a temperaturas de substrato menores de 350°C y para temperaturas mayores el material es policristalino presentando la fase monoclínica típica del HfO2. En esta investigación se estudiaron las características catodoluminiscentes de esas películas como función de dos parámetros de depósito: las temperaturas de substrato y las concentraciones en solution de los iones activadores de la luminiscencia: Tb3+ y Eu3+. Las películas excitadas con el haz de electrones presentan intensas emisiones de luz visible y sus espectros presentan bandas correspondientes a las emisiones típicas de los iones Tb3+ y Eu3+. A medida que las temperaturas de substrato durante los depósitos se incrementan, se observa un aumento de las intensidades de emisión obtenidas por catodoluminiscencia. También se obtiene una inhibición de la intensidad de las emisiones a partir de ciertos valores de la concentración de los iones activadores de la luminiscencia. Además, se presentan los resultados de las composiciones químicas de los materiales depositados y las características de la morfología superficial de las películas.

By means of the ultrasonic spray pyrolysis technique, trivalent europium doped hafnium oxide films were deposited. These films are amorphous at substrate temperatures lower than 350°C, for higher substrate temperatures the films are polycrystalline presenting the HfO2 monoclinic phase. The photoluminescence spectra for these films were studied as a function of the substrate temperature and the doping concentration. Samples excited with 395 nm radiation showed photoluminescence emission bands centered at 578, 591, 598, 612, 653 and 703 nm, associated to the electronic transitions of the trivalent europium. As the substrate temperatures are increased, an increment of the photoluminescence emission intensity was detected. Also, a concentration quenching of the photoluminescence intensity was observed. In addition, the chemical compositions of the deposited coatings and the characteristics of their surface morphologies are shown. The excitation band peaked at 395 nm, makes this material an excellent candidate for applications in solid state white lamps.

Mediante la técnica de rocío pirolítico ultrasónico, se depositaron películas de óxido de hafnio activadas ópticamente con europio trivalente. Estas películas son amorfas a temperaturas de substratos menores de 350°C, mientras que para temperaturas mayores las películas son policristalinas presentando la fase monoclínica del HfO2. Se estudiaron los espectros fotoluminiscentes de esas películas como función de algunos parámetros de depósito, tales como las temperaturas de substratos y las concentraciones del ion activador (Eu3+). Excitando con radiación de una longitud de onda de 395 nm, todos los espectros de emisión fotoluminiscente presentan bandas centradas en 578, 591, 598, 612, 653 y 703 nm, asociadas a las transiciones electrónicas del europio trivalente. A medida que las temperaturas de substratos se incrementan, se observa un aumento de las intensidades fotoluminiscentes. Asimismo, se observa una inhibición de la intensidad de la fotoluminiscencia a partir de determinados valores de la concentracion del ion activador. También se muestran los resultados de las composiciónes químicas de los materiales depositados y las características de la morfología superficial de dichas películas. La banda principal de excitación, centrada en 395 nm, hace de este material un excelente candidato para aplicaciones en lámparas de estado sólido con emisión de luz blanca.

In order to have optoelectronic function integrated in a single chip, it is very important to obtain a silicon compatible material with an optimal Photoluminescence (PL) response. The Silicon Rich Oxide (SRO) has shown intense PL and is also compatible with silicon technology. In this work, the composition and optical properties of the SRO films are studied using null Ellipsometry, Fourier Transformed Infrared spectroscopy (FTIR), and Photoluminescence (PL). The SRO films were annealed at high temperature during different times. The IR absorption spectra show the presence of three characteristics Si-O-Si vibrations modes in SiO2. However, changes in their intensity and position were observed when annealing time and silicon excess were varied. These changes are directly related with structural variation in the SRO films. PL spectra show a considerable emission in the range 650 to 850 nm that varies with different thermal treatment times.

A two-step synthesis process was performed to obtain TlBa2Ca2Cu3Ox (Tl-1223) superconductor films. The synthesized films were obtained under different thallium diffusion conditions in a two-zone furnace precursor films were deposited at 550° C on silver substrates using the spray pyrolysis technique from acetylacetonates (2, 4-pentanedionates) as reagents. Second, a thallium diffusion process is carried out to incorporate Tl in the films. For this task Tl2O3 pellets, as a Tl source, were used at 750°C. Different oxygen flow rates at atmospheric pressure were used in order to get the thallous oxide p (Tl2O) partial pressure in the range of 6.9 x 10-4 to 6.1 x 10-2 atm. The Tl-1223 phase was obtained in all cases, though for a low p (Tl2O), the films presented the BaCuO2 phase mixed with the Tl-1223 one. Critical temperature (T C) values for these films were in the range of 90 to 102 K.

El proceso de síntesis de dos pasos fue realizado para obtener películas superconductoras de TlBa2Ca2Cu3Ox (Tl-1223). Las películas sintetizadas fueron obtenidas bajo diferentes condiciones de difusión de talio en un horno de dos zonas. En el primer paso, las películas precursoras se depositaron a 550°C sobre substratos de plata usando la técnica de rocío Pirólitico a partir de acetilacetonatos (2,4-pentanedionatos) como reactivos. En el segundo paso, se llevo a cabo un proceso de difusión de talio para incorporar Tl en las películas. Para esta tarea, se usaron pastillas de Tl2O3 como fuente de talio a 750°C. Se usaron diferentes razones de flujo de oxígeno a presión atmosférica para obtener presiones parciales de óxido taloso p (Tl2O)en el intervalo de 6.9 x 10-4 to 6.1 x 10-2 atm. La fase Tl-1223 se obtuvo en todos los casos, aunque a bajas presiones parciales de p (Tl2O), las películas presentan la fase BaCuO2 mezclada con la fase Tl-1223. Los valores de temperatura crítica para estas películas se encuentran en el intervalo de 90 a 102 K.

Electrical characteristics of thin films of aluminum oxide prepared by spray pyrolysis were studied. The films were prepared from solution onto single crystal GaAs (100) substrates at temperatures from 300°C to 600°C. The electrical characteristics of these films as a function of the substrate temperature were determined from the capacitance and current versus voltage measurements of metal-oxide-semiconductor (MOS) structures incorporating them. The interface states density was of the order of 10(12) 1/eV-cm² and the films can stand electric fields higher than 5MV/cm, without observing destructive dielectric breakdown. The refractive index at 633 nm near to 1.64 was measured by ellipsometry.

Se estudiaron las características eléctricas de películas delgadas de óxido de aluminio preparadas por la técnica de rocío pirolítico ultrasónico. Las películas delgadas se depositaron a partir de una solución de acetilacetonato de aluminio en N,N-dimetilformamida sobre substratos monocristalinos de GaAs (100) tipo-p. La temperatura de depósito fue de 300 a 600 ºC. Las propiedades eléctricas de las películas en función de la temperatura de substrato se determinaron por medidas de capacitancia y corriente contra voltaje mediante la incorporación de las películas en estructuras tipo MOS (metal-óxido-semiconductor). La densidad de estados de interfaz resultó del orden de 10(12) 1/eV-cm² y el dispositivo MOS soportó campos eléctricos mayores a 5MV/cm, sin mostrar rompimiento dieléctrico. El índice de refracción se determinó por elipsometría a 633nm, con un valor máximo del orden de 1.64.

IBA methods were applied to measure elemental depth profiles of precursors and superconducting MgB2 thin films deposited on glassy carbon (Good Fellows) and sapphire (Al2O3) substrates. For each type of substrates we obtained a pair of samples i.e. one amorphous precursor and one superconducting film which were then characterized. A ³He+ beam was used to bombard both, precursors and superconducting films in order to obtain the samples elemental composition profiles. The zero resistance Tco and the middle of transition Tcm values were 26.0K and 29.7K for the MgB2 film deposited on glassy carbon substrate. In the case of sapphire substrate the Tco and Tcm values were 25.0K and 27.9K, respectively.

Bombardeo de materiales con haces de iones producidos por un acelerador de partículas fueron usados para medir la composición elemental y su perfil en profundidad de películas delgadas superconductoras de MgB2depositadas sobre sustratos de carbon vidriado (Good Fellows) y zafiro (Al2O3). Para cada tipo de sustrato, obtuvimos un par de muestras, es decir, película precursora amorfa y película superconductora, las cuales fueron caracterizadas. Un haz de ³He+fue usado para bombardear tanto las películas precursoras y superconductoras para obtener su composición elemental. Los valores de la resistencia nula Tco y la resistencia media de transicion Tcm fueron 26.0 K y 29.7 K para las películas superconductoras de MgB2depositadas sobre los sustratos de carbón vidriado. En el caso cuando se uso zafiro como sustrato los valores deTco y Tcm fueron 25.0 K y 27.9 K.

Abstract Silicon rich oxide films (SRO) were obtained by silicon implantation in silicon dioxide and PE - LPCVD techniques. Also, PECVD and LPCVD SRO films were implanted with silicon to get super-enriched SRO. Photo- and Cathodo- Luminescence (PL and CL) studies of these materials are presented. All the samples show similar bands related with an excess of silicon, but with different behavior in the intensity of the signal. PL results from silicon implanted LPCVD films show an emission stronger than the emission from the other films under study. The strongest PL intensity is related with an optimum annealing time and an optimum silicon excess, and consequently with an optimum size of the nanocrystals.

Resumen Se obtienen películas de oxido rico en silicio (SRO) por implantación de silicio en dióxido de silicio y por técnicas PE-LPCVD. También las películas PECVD y LPCVD se implantan con silicio para obtener SRO uperenriquecido. Se presentan estudios de Foto y Cátodoluminiscencia (Pl y CL) de estos materiales. Todas las muestras muestran bandas similares relacionadas cpon un exceso de silicio, pero con diferente comportamiento en la intensidad de la señal. Los resultados de PL de las películas LPCVD implantadas con silicio muestran una emisión más intensa que la emisión de las otras pelçículas bajo estudio. La mayor intensidad de luminiscencia está relacionada con un tiempo de aleación óptimo y con un exceso de silicio óptimo, y consecuentemente con tamaño óptimo de los nanocristales.

Two superconducting models of transmission cables were designed, constructed and tested for the first time in México, the 1m model and 5m model with parameters of practical applications 23 kV/2kA. For this purpose also a new cryogenic laboratory was built and equipped with all necessary devices and instruments. For construction of both models, a high critical temperature superconducting Bi-Sr-Ca-Cu-O tape was used. The design, construction and performed tests are briefly described and some preliminary results of test measurements are presented.

Por primera vez en México, se han diseñado, construido y probado dos modelos superconductores de transmisión de energía eléctrica de una longitud de 2 m y de 5 m con parámetros prácticos para aplicación de 23kV/2kA. Con este propósito se construyó también un laboratorio de criogenia nuevo, equipado con todos los dispositivos e instrumentos requeridos. En la construcción de ambos modelos, se utilizó cinta superconductora de Bi-Sr-Ca-Cu-O. Se presentan la descripción y construcción del diseño, así como las pruebas realizadas y los resultados preliminares de las mediciones efectuadas son presentados.