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Tepetitla, Mexico
Tepetitla, Mexico

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Diaz-Reyes J.,CIBA IPN | Galvan-Arellano M.,CINVESTAV | Castillo-Ojeda R.S.,Polytechnic University of Pachuca | Pena-Sierra R.,CINVESTAV
Vacuum | Year: 2010

We present the electrical and structural characterization of AlxGa1-xAs layers grown in a metallic-arsenic-based-MOCVD system. The gallium and aluminium precursors were the metal-organic compounds trimethylgallium (TMGa) and trimethylaluminium (TMAl), respectively. AlxGa1-xAs layers that were grown at temperatures less than 750 °C present a high electrical resistivity. Independent of the used III/V ratio the samples that were grown at temperatures greater that 750 °C were n-type with an electron concentration of around 1017 cm-3 and a carrier mobility of 2200 cm2/V-s. Chemical composition studies by SIMS exhibit the presence of silicon, carbon and oxygen as the main residual impurities. Silicon concentration of around of 1017 cm-3 is very close to the free carrier concentration determined by the Hall-van der Pauw measurements. Composition homogeneity and structural quality are demonstrated by Raman measurements. As the growth temperature is increased the layers compensation decreases but the Raman spectra show that the crystalline quality of the layers diminishes. © 2009 Elsevier Ltd. All rights reserved.


Fernandez-Luqueno F.,CINVESTAV | Lopez-Valdez F.,CIBA IPN | Dendooven L.,CINVESTAV | Luna-Suarez S.,CIBA IPN | Ceballos-Ramirez J.M.,CINVESTAV
Applied Soil Ecology | Year: 2016

Wastewater sludge is used worldwide to dissipate hydrocarbon in PAHs-polluted soils. However, little is known about why wastewater sludge stimulates and accelerates the removal of polycyclic aromatic hydrocarbons (PAHs) from soils. Soil of the former lake Texcoco with pH 9 and electrical conductivity 7dSm-1 was contaminated with phenanthrene and anthracene, and amended or not with wastewater sludge sterilized or not, and with or without polyacrylamide while phenanthrene and anthracene were monitored in an aerobic incubation experiment of 112 days. An agricultural soil from Acolman and wastewater sludge treated in the same way served as controls. After 112 days, the largest dissipation of anthracene and phenanthrene was found in the Acolman soil amended or not with wastewater sludge with or without polyacrylamide. The largest dissipation of anthracene and phenantrene from both soils was found in soils amended with wastewater sludge and polyacrylamide, while the lowest degradation of PAHs was detected in unamended PAHs-polluted sludge and in soils amended with sterilized wastewater sludge. It was found that polyacrylamide accelerated removal of PAHs from soils, while wastewater sludge increased the removal of PAHs from soils but the effect is controlled by the physical, chemical and microbial soil properties, the contaminant and microorganisms in wastewater sludge. © 2016 Elsevier B.V.


Martinez-Juarez J.,CIDS ICUAP | Diaz-Reyes J.,CIBA IPN | Juarez-Diaz G.,CINVESTAV | Galeazzi R.,CIDS ICUAP | Galvan-Arellano M.,CINVESTAV
Materials Science Forum | Year: 2010

Zinc oxide (ZnO) is a direct, wide band gap semiconductor material having many promising properties for UV/blue optoelectronics, transparent electronics, spintr spintronic devices and onic sensor applications. The ZnO is synthesized by the technique of Chemical Bath Deposition by microwaves heating (MW-CBD). The urea concentration in the solution is varied, maintaining constant t the zinc nitrate in ratio 1:1 ... 1:10. The physi physical properties of ZnO thin films were examined by X-ray diffraction (XRD), SEM SEM-EDS, and Raman scattering, which are convenient tools that can provide us with plenty of information about crystal structure and elementary excitons. By X X-rays one obtains that it has hexagonal polycrystalline wurtzite type structure. The IR absorption line at 3577 cm cm-1 detected at 300 K in bath chemical ZnO is assigned an O-H bond primarily aligned with the c c-axis of the crystal and bonding between Zn Zn-O (473cm 473cm-1, 532 cm , cm-1). The Raman spectra show the first order experimental Raman spectra of ZnO excited by 514.5 nm laser line. The first order Raman modes A1T, E1T, E 2(H), A1Land E1L are identified as the peaks sited at 385, 426, 437, 572 and 584 cm-1. © (2010) Trans Tech Publications.


Diaz-Reyes J.,CIBA IPN | Flores-Mena J.E.,FCE BUAP | Gutierrez-Arias J.M.,FCE BUAP | Morin-Castillo M.M.,FCE BUAP | And 4 more authors.
Advances in Sensors, Signals and Materials - 3rd WSEAS International Conference on Sensors and Signals, SENSIG'10, 3rd WSEAS International Conference on Materials Science, MATERIALS'10 | Year: 2010

This work presents a study of effect of annealing temperature on optical and structural properties of WO3 that has been deposited by hot-filament metal oxide deposition (HFMOD). X-ray diffraction shows that the as-deposited WO3 films present mainly monoclinic crystalline phase. The Raman spectrum shows four intense peaks that are typical Raman peaks of crystalline WO3 (m-phase) that corresponds to the stretching vibrations of the bridging oxygen that enhance and increase their intensity with the annealing temperature. gap can be varied from 2.92 to 3.15 eV by annealing WO3 from O to 500°C. The photoluminescence response of the asdeposited film presents two radiative transitions centered at 2.04 and 2.65 eV that are associated to oxygen vacancies.


Diaz-Reyes J.,CIBA IPN | Martinez-Juarez J.,CIDS ICUAP | Galeazzi R.,CIDS ICUAP | Juarez-Diaz G.,CIDS ICUAP | And 3 more authors.
Advances in Sensors, Signals and Materials - 3rd WSEAS International Conference on Sensors and Signals, SENSIG'10, 3rd WSEAS International Conference on Materials Science, MATERIALS'10 | Year: 2010

ZnO has received increasing attention and been recognized as a promising candidate for applications due to its optoelectronic properties in the UV range. The ZnO is grown by the technique of Chemical Bath Deposition activated by microwaves (CBD-μW). X-rays scattering yields a hexagonal polycrystalline wurtzite type structure. The Raman spectra present four main peaks at 444, 338, 104 and 78 cm-1 associated to the modes E2 high, (E2 high - E2 low), E 2 low and an unidentified band. The 300 K photoluminescence presents visible/UV radiative bands associated to vacancies of zinc and oxygen. In addition, it was carried out energy dispersive spectroscopy (EDS) measurements on the films to determine their stoichiometry, relating the intensity of radiative bands associated to oxygen and zinc vacancies.


Diaz-Reyes J.,CIBA IPN | Rodriguez-Fragoso P.,CINVESTAV | Mendoza-Alvarez J.G.,CINVESTAV
Journal of Luminescence | Year: 2013

Quaternary layers were grown by liquid phase epitaxy on (1 0 0) GaSb substrates under lattice-matching conditions. The low-temperature photoluminescence of p-type InxGa1-xAsySb 1-y was obtained as a function of incorporated zinc concentration. The photoluminescence spectra were interpreted using a model which takes into account nonparabolicity of the valence band. Calculations of the peak position and photoluminescence transitions were performed. Both the band filling as well as band tailing due to Coulomb interaction of free carriers with ionized impurities and shrinkage due to exchange interaction between free carriers were considered in order to properly account for the observed features of photoluminescence spectra. It is proposed that low-temperature photoluminescence band-to-band energy transition can be used to obtain the carrier concentration in p-type InxGa1-xAsySb1-y. This method could be used to estimate free carrier concentration ranging from 6.036×1016 to 1.350×1018 cm-3. © 2012 Elsevier B.V. All rights reserved.


Diaz-Reyes J.,CIBA IPN | Flores-Mena J.E.,FCE BUAP | Gutierrez-Arias J.M.,FCE BUAP | Morincastillo M.M.,FCE BUAP | And 2 more authors.
Advances in Sensors, Signals and Materials - 3rd WSEAS International Conference on Sensors and Signals, SENSIG'10, 3rd WSEAS International Conference on Materials Science, MATERIALS'10 | Year: 2010

This work presents the characterization of p-type GaAs layers highly doped with carbon grown in a metallic-arsenic-based-MOCVD system. The gallium precursor was the compound trimethylgallium (TMG) and elemental arsenic as precursor of arsenic, respectively. The influence of the doping in the optical and structural properties of the GaAs layers has been studied by photoluminescence (PL) and Raman dispersion measurements, Hall effect and High resolution X-ray diffraction (HRXRD). In order to dope with carbon in the range of 1016 to 1020 cm-3, it was necessary to modify the activity of hydrogen in the growth atmosphere with the control of a mixture H2+N2, which was used like carrying gas. The PL and Raman scattering responses of the samples are strongly dependence of the growth temperature, which were investigated based on the hole concentration. Device quality GaAs layers have been grown in a broad range of growth temperatures.


Diaz-Reyes J.,CIBA IPN | Martinez-Juarez J.,CIDS ICUAP | Garcia M.L.,CIDS ICUAP | Juarez G.,CINVESTAV | Galeazzi R.,CIDS ICUAP
IOP Conference Series: Materials Science and Engineering | Year: 2014

A study of the growth and the physical properties of ZnO films deposited by chemical bath technique and annealed by microwave are presented. For the deposition solution the molar ratio between zinc nitrate and urea is varied in a range of 1:1... 1:10. By X-ray obtains that layers have hexagonal polycrystalline wurtzite type unitary cell. The Raman spectra show the first order experimental Raman spectra of ZnO. The first order Raman modes are identified in the ZnO Raman spectra. The 300K photoluminescence shows radiative bands labelled by red, yellow, green and violet bands, which are associated to defects of oxygen and zinc vacancies. By EDS measurements determined their stoichiometry, which allows relating it with the intensity of radiative bands associated to oxygen and zinc vacancies. © 2010 IOP Publishing Ltd.


Galvan-Arellano M.,CINVESTAV | Diaz-Reyes J.,CIBA IPN | Pena-Sierra R.,CINVESTAV
Vacuum | Year: 2010

Ohmic contacts with a palladium (Pd) diffusion barrier were formed on GaAs substrates. The metal-contact structure consists of a gold-based-alloy/Pd/semiconductor-substrate. Characteristics of the deposited Pd films by "electroless" deposition on semiconductor-substrates are reported. SIMS analysis realized on the metal-semiconductor structures demonstrates the capability of the Pd films to act as a diffusion barrier. Contact resistance of the ohmic contacts was measured by the transmission line method (TLM). © 2009 Elsevier Ltd. All rights reserved.

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