Papers by JAIRO ARMANDO CARDONA BEDOYA
physica status solidi (b), 2002
We present results on the growth of GaInNAs semiconductor thin films which present evidence of a ... more We present results on the growth of GaInNAs semiconductor thin films which present evidence of a nanocrystalline GaAs background. The films were grown using the radio frequency sputtering deposition technique in a working gas atmosphere mixture of argon and nitrogen. X-ray diffractograms show evidence of the presence of a phase of GaInNAs material with high N concentration, and of a phase of GaAs material with crystallite sizes in the order of nanometers. From the absorption spectra measured by the photoacoustic technique we show that we have obtained the GaInNAs alloys with variable band gap energies, but also that this alloy is embedded in a background of nanocrystalline GaAs material. We discuss the nature of this formation, the quantum confinement effects evidenced from the absorption spectra, and the grain sizes obtained from the use of a spherical quantum dot model.
Journal of Nanoparticle Research, 2007
Page 1. BRIEF COMMUNICATION Effect of thermal annealing on rf sputtering-deposited nanocrystallin... more Page 1. BRIEF COMMUNICATION Effect of thermal annealing on rf sputtering-deposited nanocrystalline GaNxAs1Àx thin films Jairo A. Cardona-Bedoya Æ Alfredo Cruz-Orea Æ Orlando Zelaya-Angel Æ Julio G. Mendoza-Alvarez ...
Applied Surface Science, 2004
The search for semiconductors with band gap energies in the green–blue region of the visible spec... more The search for semiconductors with band gap energies in the green–blue region of the visible spectra has stimulated the development of new ternaries in the II–VI and III-nitrides systems. In the GaN-side of the GaNAs ternary compound it is expected that the band gap energy could be adjusted for all the visible spectra by changing the N concentration in the
Applied Physics Letters, 2002
Using the radio-frequency (rf) sputtering deposition technique, we have grown GaInNxAs1−x thin fi... more Using the radio-frequency (rf) sputtering deposition technique, we have grown GaInNxAs1−x thin films on glass substrates at room temperature. The concentration of nitrogen in the films was found to depend mainly on the rf power used to excite the growth plasma. X-ray diffractograms show that the films have small grain sizes and present a broad diffraction band centered close to the (002) diffraction peak of hexagonal GaN. Electron dispersive spectroscopy measurements report N concentrations of x∼0.8 and In concentrations of about 3% indicating that we have grown GaInNxAs1−x alloys in the GaN-rich side. The absorption spectra measured by the photoacoustic technique show that these semiconductor films have band-gap energies ranging between 1.69 and 2.56 eV, when the rf sputtering power is varied in the range 30–80 W. Thus, we show the feasibility to grow GaInNxAs1−x thin films with high N concentrations in which we can tune the band-gap energy in the red-blue portion of the visible sp...
GaN x As 1−x ternary alloys in the GaN-rich side, are expected theoretically to have band-gap ene... more GaN x As 1−x ternary alloys in the GaN-rich side, are expected theoretically to have band-gap energies in the full range of the visible spectrum for just a small change in the nitrogen concentration in the range of about 70-85%. Using the r. f. sputtering and the laser ablation film deposition techniques, we have reported the growth of ternary GaNAs layers with band-gap energies in the range between 1.4 to 2.6 eV. In this work we report the growth of GaNAs thin films on Si substrates using the r. f. sputtering technique at high substrate temperatures; the r. f. power was varied in order to control the nitrogen incorporation in the films. The low temperature photoluminescence (PL) and the photoacoustic (PA) spectroscopies were used to characterize the optical properties of the series of GaN x As 1−x As films grown with different stoichiometries. We discuss the origin of the transitions observed in the PL spectra and the shoulders around 2.5 eV observed in the PA spectra.
Disponible en línea en: www.javeriana.edu.co/universitas_scientiarum
La segregación superficial de átomos en las aleaciones de semiconductores III-V produce interface... more La segregación superficial de átomos en las aleaciones de semiconductores III-V produce interfaces abruptas y modifica los perfiles del potencial, alternando los estados electrónicos en el pozo cuántico y la energía de emisión en el espectro de fotoluminiscencia. En este trabajo se resuelve mediante serie de potencias la ecuación de Schrödinger considerando un potencial simétrico tipo Cauchy, el cual es suave y decreciente al infinito. Se propone dicho potencial debido a los cambios en el perfil del potencial del pozo cuántico por la segregación de átomos durante el proceso de crecimiento. Se determinó la energía del estado base en función de los parámetros que caracterizan este potencial. Este modelo fue aplicado al caso particular de la segregación de indio en el sistema InGaAs/GaAs. La energía de transición del estado base se calcula a partir de las diferencias de energía entre el electrón y el hueco en función del ancho del pozo. Dichos cálculos están de acuerdo con los picos de...
Universitas Scientiarum, 2018
Textile industries produce effluent waste water that, if discharged, exerts a negative impact on ... more Textile industries produce effluent waste water that, if discharged, exerts a negative impact on the environment. Thus, it is necessary to design and implement novel waste water treatment solutions. A sequential treatment consisting of ligninolytic co-culture with the fungi Pleurotus ostreatus and Phanerochaete crhysosporium (secondary treatment) coupled to TiO2/UV photocatalysis (tertiary treatment) was evaluated in the laboratory in order to discolor, detoxify, and reuse textile effluent waste water in subsequent textile dyeing cycles. After 48 h of secondary treatment, upto 80 % of the color in the waste water was removed and its chemical and biochemical oxygen demands (COD, and BOD5) were abated in 92 % and 76 %, respectively. Laccase and MnP activities were central to color removal and COD and BOD5 abatement, exhibiting activity values of 410 U.L-1 and 1 428 U.L-1, respectively. Subjecting waste water samples to 12h of tertiary treatment led to an 86 % color removal and 73 % an...
Universitas Scientiarum, 2012
Objective. Removal and detoxification of azo dye by photocatalysis with TiO2. Materials and metho... more Objective. Removal and detoxification of azo dye by photocatalysis with TiO2. Materials and methods. TiO2 films were prepared by sedimentation at pH 1.3, using as support a borosilicate glass, annealed for 1 hour at 450 °C. Physical characterization was performed by Scanning Electron Microscopy, X-ray diffraction and UV/VIS spectrometry. Dye Black Reactive 5 removal was carried-out in a quartz photo-reactor. Results. Optical characterization revealed the films displayed evident TiO2 spherical particles of various irregular sizes, porous, and without fractures. The average crystal size was 77.5 nm and 77.7 nm for 50 °C (dried temperature) and 450 ºC (annealed temperature) respectively. The energy of the band gap (GAP) was 3.02 and 2.68 eV respectively. Maximum concentration of dye that negatively affected color removal was 80 mg/L (17%). At lower dye’s concentrations (10, 50 and 70mg/L) decolorization was greater than 80%. TiO2 films were reused for five consecutive cycles of 6 hours...
(ICEEE). 1st International Conference on Electrical and Electronics Engineering, 2004.
ABSTRACT Not Available
physica status solidi (c), 2004
ABSTRACT The influence of tellurium doping on the optical properties of InxGa1–xAsySb1–y epitaxia... more ABSTRACT The influence of tellurium doping on the optical properties of InxGa1–xAsySb1–y epitaxial layers has been studied by photoluminescence (PL) spectroscopy. PL was carried out by exciting the sample with the 488-nm line of an Ar-ion laser, changing the exciting power in the range between 40–200 mW and varying the temperature in the range 15–300 K. For the low-doped sample the PL spectrum showed a narrow exciton-related peak at 648.6 meV with a full width at half maximum (FWHM) of about 7 meV, which is an evidence of the good crystalline quality of the layers. For higher Te doping, the PL spectra showed the presence of band-to-band and donor-to-acceptor transitions which overlap as the Te concentration increases. The peak of the PL band shifts to higher energies as Te doping increases due to a band-filling effect as the Fermi level enters into the conduction band. The temperature dependence of the PL spectra for those samples with higher Te doping show a broad band at intermediate energies which disappear for temperatures above 80 K which is a typical behavior for a transition associated to DX deep defects. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Journal of Physics: Condensed Matter, 2003
Applied Surface Science, 2004
GaSb-based semiconductors are being developed because of the possibility to grow materials with b... more GaSb-based semiconductors are being developed because of the possibility to grow materials with band-gap energies covering a substantial range of the medium infrared spectrum. In particular, GaInAsSb alloys can be grown epitaxially on GaSb and InAs substrates, resulting in semiconductor layers with band-gap energies in the range 0.8–4.3μm. In this work we present results on the study of the influence
Quaternary semiconductor GaInNAs films were grown by r.f. sputtering using as a target a GaAs cry... more Quaternary semiconductor GaInNAs films were grown by r.f. sputtering using as a target a GaAs crystal with small In pieces and a mixture of Ar and N gases to produce the plasma in the sputtering chamber. Growth parameters were optimized to produce films with thicknesses of several tenths of a micron. We were able to grow GaInNAs films with different
The photocatalytic activity of TiO 2 thin films in wastewater, under an UV irradiation, is studie... more The photocatalytic activity of TiO 2 thin films in wastewater, under an UV irradiation, is studied. The films were prepared on corning glass substrates by the sputtering RF technique. We present evidence on the photocatalytic degradation, carried out by advanced oxidation processes (AOPs) in domestic wastewater pretreated with UASB (upflow anaerobic sludge blanket) reactors. TiO 2 films were illuminated with ultraviolet light during a time of 4 hours (λ ∼ = 264 nm). We could see the effect of degraded operation in the absorbance measurement using UV-VIS spectrophotometry. The results show an increased rate of degradation of the wastewater by 30% compared to the values reflected biologically treated wastewater by anaerobic reactors.
Review of Scientific Instruments, 2003
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Papers by JAIRO ARMANDO CARDONA BEDOYA