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209 results on '"Santoyo-Salazar, J."'

2. Enhanced ZnTe infiltration in porous silicon by Isothermal Close Space Sublimation

Author

de Melo, C., Larramendi, S., Costa, V. Torres, Santoyo-Salazar, J., Behar, M., Dias, J. Ferraz, and de Melo, O.

Subjects
Condensed Matter - Materials Science
Abstract

Isothermal Close Space Sublimation (ICSS) technique was used for embedding porous silicon (PS) films with ZnTe. It was studied the influence of the preparation conditions and in particular of a chemical etching step before the ZnTe growth, on the composition profile and final porosity of ZnTe embedded PS. The structure of the embedded material was determined by x-ray diffraction analysis while the thickness of the samples was determined by scanning electron microscopy (SEM). Rutherford backscattering (RBS) and Energy Dispersive (EDS) spectrometries allowed determining the composition profiles. We conclude that the etching of the PS surface before the ZnTe growth has two main effects: the increase of the porosity and enhancing the reactivity of the inner surface. It was observed that both effects benefit the filling process of the pores. Since RBS and EDS cannot detect the porosity in the present system, we explore the evolution of porosity by the fitting of the UV-VIS reflectance spectra. The atomic percent determined with this method was in relatively good agreement with that obtained from the RBS and EDS measurements., Comment: This article appeared in Microporous and Mesoporous Materials 188 2014 93 98 and may be found at www.sciencedirect.com/science/article/pii/S138718111400019

Published
2019
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25. Interference and electro-optical effects in cubic GaN/GaAs heterostructures prepared by molecular beam epitaxy.

Author

Zendejas-Leal, B. E., Casallas-Moreno, Y. L., Yee-Rendon, C. M., González-Pedreros, G. I., Santoyo-Salazar, J., Aguilar-Hernández, J. R., Vázquez-López, C., Gallardo-Hernández, S., Huerta-Ruelas, J., and López-López, M.

Subjects
MOLECULAR beam epitaxy, ELECTRO-optical effects, AUDITING standards, THERMO-optical effects, HETEROSTRUCTURES, OPTICAL interference
Abstract

Cubic GaN (c-GaN) samples on GaAs (0 0 1) substrates were grown by RF-plasma-assisted molecular beam epitaxy, in which an As4 overpressure was employed for the nucleating layer. Photoreflectance spectra were obtained in the temperature range from 14 to 300 K. Two independent phenomena were noticed. The first one consisted in optical interference features below the c-GaN bandgap, whose origin is a thermo-optical effect: the ultraviolet perturbation beam changes the refractive index of the c-GaN. The second one represents electro-optical phenomena in which two classical band-to-band transitions occur: the first transition for c-GaN layer in which the temperature dependence reveals defects in the film attributed to a hexagonal fraction estimated previously between 3% and 10%, and a second transition for the GaAs substrate that shows Franz–Keldysh oscillations. [ABSTRACT FROM AUTHOR]

Published
2020
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41. Influence of plasma parameters and substrate temperature on the structural and optical properties of CdTe thin films deposited on glass by laser ablation.

Author

Quiñones-Galván, J. G., Camps, Enrique, Campos-González, E., Hernández-Hernández, A., Santana-Aranda, M. A., Pérez-Centeno, A., Guillén-Cervantes, A., Santoyo-Salazar, J., Zelaya-Angel, O., and de Moure-Flores, F.

Subjects
THERMAL stresses, THERMAL strain, THERMODYNAMIC state variables, GLASS sealants, THIN films
Abstract

In the pulsed laser deposition of thin films, plasma parameters such as energy and density of ions play an important role in the properties of materials. In the present work, cadmium telluride thin films were obtained by laser ablation of a stoichiometric CdTe target in vacuum, using two different values for: substrate temperature (RT and 200 °C) and plasma energy (120 and 200 eV). Structural characterization revealed that the crystalline phase can be changed by controlling both plasma energy and substrate temperature; which affects the corresponding band gap energy. All the thin films showed smooth surfaces and a Te rich composition. [ABSTRACT FROM AUTHOR]

Published
2015
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43. Growth Mechanism and Properties of Self-Assembled InN Nanocolumns on Al Covered Si(111) Substrates by PA-MBE

Author

Casallas-Moreno, Y. L., primary, Gallardo-Hernández, S., additional, Yee-Rendón, C. M., additional, Ramírez-López, M., additional, Guillén-Cervantes, A., additional, Arias-Cerón, J. S., additional, Huerta-Ruelas, J., additional, Santoyo-Salazar, J., additional, Mendoza-Álvarez, J. G., additional, and López-López, M., additional

Published
2019
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47. Physical properties of CdTe:Cu films grown at low temperature by pulsed laser deposition.

Author

de Moure-Flores, F., Quiñones-Galván, J. G., Guillén-Cervantes, A., Arias-Cerón, J. S., Contreras-Puente, G., Hernández-Hernández, A., Santoyo-Salazar, J., de la L. Olvera, M., Santana-Aranda, M. A., Zapata-Torres, M., Mendoza-Álvarez, J. G., and Meléndez-Lira, M.

Subjects
PULSED laser deposition, SUBSTRATES (Materials science), THIN films, X-ray diffraction, COPPER films
Abstract

CdTe:Cu films were grown by pulsed laser deposition on Corning glass slides at a substrate temperature of 300 °C. The thin films were grown using CdTe and Cu2Te powders, varying the Cu2Te concentration from 3 to 10 wt. %. The structural, compositional, optical, and electrical properties were analyzed as a function of the nominal copper concentration. X-ray diffraction shows that films have CdTe cubic phase. The compositional analysis indicates that CdTe:Cu films grown with lower Cu content have Te excess, on the other hand, films with higher Cu content have Te deficiencies. The electrical measurements showed that CdTe:Cu films grown with low Cu content present lowest resistivity. [ABSTRACT FROM AUTHOR]

Published
2012
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48. Synthesis of visible light emitting self assembled Ge nanocrystals embedded within a SiO2 matrix.

Author

Hernández-Hernández, A., Rangel-Kuoppa, V. T., Plach, Thomas, De Moure-Flores, F., Quiñones-Galván, J. G., Santoyo-Salazar, J., Zapata-Torres, M., Hernández-Hernández, L. A., and Meléndez-Lira, M.

Subjects
LIGHT emitting diodes, NANOCRYSTALS, SILICA, CRYSTALLOGRAPHY, GERMANIUM compounds
Abstract

As-grown light emitting self-assembled Ge nanocrystals (Ge-NCs) embedded in a SiO2 matrix were produced via a sequential deposition process of SiO2/Ge/SiO2 layers employing a reactive radio frequency sputtering technique. Obtained Ge-NCs show a crystallographic phase, the proportion, size, quality, and specific orientation of which are determined by the oxygen partial pressure. Photoluminescence (PL) spectra indicate that the size distribution of Ge-NCs is reduced and centered on about 8 nm when higher oxygen partial pressure is employed; the formation of Ge-NCs is corroborated by transmission electron microscopy measurements, and their sizes are consistent with estimates from PL measurements. Resistivity measurements are explained by a near neighbors hopping process, with specific features depending on the Ge-NCs' size. The features of PL and resistivity measurements indicate that there is no appreciable dependence of the number of interfacial defects on the oxygen partial pressure. [ABSTRACT FROM AUTHOR]

Published
2012
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