Investigation of proton damage in III-V semiconductors by optical spectroscopy

We studied the damage produced by 2MeV proton radiation on epitaxially grown InGaP/GaAs structure by means of spatially resolved Raman and photoluminescence (PL) spectroscopy. The irradiation was performed parallel to the sample surface in order to determine the proton penetration range in both compounds. An increase in the intensity of longitudinal optical phonons and a decrease in the luminescence were observed. We associate these changes with the creation of defects in the damaged region, also responsible for the observed change of the carrier concentration in the GaAs layer, determined by the shift of the phonon-plasmon coupled mode frequency. From the spatially resolved profile of the PL and phonon intensities, we obtained the proton range in both materials and we compared them with stopping and range of ions in matter simulations. The comparison between the experimentally obtained proton range and simulations shows a very good agreement for GaAs but a discrepancy of 20% for InGaP. This discrepancy can be explained in terms of limitations of the model to simulate the electronic orbitals and bonding structure of the simulated compound. In order to overcome this limitation, we propose an increase in 40% in the electronic stopping power for InGaP.This work was supported by BEC.AR FUNDACION YPF-CONICET 2013 (Argentina) and DFG within Grant No. SFB 787. ARG thanks the Spanish Ministry of Economy and Competitiveness (MINECO) for its support through Grant No. SEV-2015-0496 in the framework of the Spanish Severo Ochoa Centre of Excellence program.Peer reviewe

Monitoreo térmico de aulas de la Facultad de Arquitectura de la UNNE (Resistencia, Chaco) en días de invierno y condiciones reales de ocupación

Se presentan los resultados del monitoreo térmico de seis aulas del edificio de la Facultad de Arquitectura y Urbanismo (FAU) de la Universidad Nacional del Nordeste (UNNE), durante un período de 15 días de invierno, en la ciudad de Resistencia, Chaco. El objetivo fue detectar posibles problemas de disconfort y elaborar un primer diagnóstico de situación higrotérmica, en el marco de un proyecto de investigación orientado a la evaluación termoenergética de las sedes de las facultades de Arquitectura y de Ingeniería de la UNNE. Por los resultados obtenidos, el edificio monitoreado, que constituye una tipología constructiva tradicional representativa de muchos edificios institucionales de la década del ’50 (en servicio activo en varias provincias del país), constituye un caso de desempeño térmico regular durante días de invierno típicos de la zona “Ib”, con temperaturas interiores por debajo del límite inferior confortable definido, durante el 64% del tiempo de monitoreo.This work presents the thermal monitoring’s results of six classrooms of the building of Architecture and Urbanism Faculty (FAU) of Northeast National University (UNNE) during a period of 15 winter days, in Resistencia city. The objective was to detect potential thermal discomfort problems and develop an initial diagnosis of hygrothermal situation, inside a research project oriented to the thermal and energetic assessment of the Architecture and Engineering faculties buildings. As a results, the analized building, which is a traditional building type, representative of many institutional buildings of the '50s (on active duty in several argentine provinces), represents a case of regular thermal performance during typical winter days in the "Ib" zone , with internal temperatures below the lower defined comfort limit, during 64% of monitoring time.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES

In-situ and Ex-situ characterization of III-V semiconductor materials and solar cells upon 10 MEV proton irradiation

In this work we present the results and analysis of a 10 MeV proton irradiation experiment performed on III-V semiconductor materials and solar cells. A set of representative devices including lattice-matched InGaP/GaInAs/Ge triple junction solar cells and single junction GaAs and InGaP component solar cells and a Ge diode were irradiated for different doses. The devices were studied in-situ before and after each exposure at dark and 1 sun AM0 illumination conditions, using a solar simulator connected to the irradiation chamber through a borosilicate glass window. Ex-situ characterization techniques included dark and 1 sun AM0 illumination I-V measurements. Furthermore, numerical simulation of the devices using D-AMPS-1D code together with calculations based on the TRIM software were performed in order to gain physical insight on the experimental results. The experiment also included the proton irradiation of an unprocessed Ge solar cell structure as well as the irradiation of a bare Ge(100) substrate. Ex-situ material characterization, after radioactive deactivation of the samples, includes Raman spectroscopy and spectral reflectivity

Effects of 10 MeV proton irradiation on III-V solar cells

In this work we present our latest results and analysis of a 10 MeV proton irradiation experiment performed on III-V solar cells. A set of representative devices were irradiated for different fluences, including latticematched GaInP/GaInAs/Ge triple junction, GaInP/Ge double junction, and GaAs and Ge single junction solar cells. The methodology applied included the irradiation of two devices of each type; for a better control of the measurements, non-irradiated devices with the same characteristics of those irradiated were used as reference. The devices were monitored before and after each exposure by in-situ characterization of the electrical response under dark and under illumination using a solar simulator connected to the irradiation chamber through a borosilicate glass window. Ex-situ characterization techniques included dark and 1 sun AM0 illumination I-V curve and external quantum efficiency measurements. Furthermore, results of the numerical simulation of devices with D-AMPS-1D code are presented in order to give a physical interpretation of the results. DLTS spectroscopy preliminary results for single junction GaAs cells are also presented

Implementación de estrategias de apoyo pedagógico basada en la determinación de perfiles de rendimiento académico

[6 p.]il.Actualmente la deserción de alumnos universitarios en los primeros años de las carreras tiene un alto impacto en la planificación y asignación de recursos de las Universidades. Es por ello que continuamente se buscan alternativas para paliar esta situación. Una de ellas es la detección temprana de los posibles casos de deserción y la consecuente implementación de estrategias que permitan mejorar el rendimiento académico del alumno. En este sentido, en el proyecto de investigación Determinación de Perfiles de Rendimiento Académico a través de Data Mining, llevado a cabo durante los años 2013 a 2015 en la Universidad Tecnológica Nacional Facultad Regional Resistencia, se desarrolló un modelo predictivo que permite pronosticar la probabilidad de que los estudiantes del ciclo lectivo 2016 tengan un perfil de bajo rendimiento académico en la Cátedra Algoritmos y Estructuras de Datos. Posteriormente sobre este grupo de alumnos se decidió implementar diferentes estrategias pedagógicas, con el objetivo de disminuir el nivel de deserción y de alumnos libres durante la cursada del corriente año. El presente trabajo describe el modelo basado en tutorías individuales para la mencionada cátedra, y evalúa los resultados posteriores a la aplicación de las tutorías y propone otras alternativas para dar apoyo académico a los alumnos con bajo rendimiento.Fil: Torre, Juliana I.. Universidad Católica de Salta. Facultad de Ingeniería e Informática; Argentina.Fil: Báez Molinas, María E.. Universidad Católica de Salta. Facultad de Ingeniería e Informática; Argentina.Fil: Yaccuzzi, Nelson S.. Universidad Católica de Salta. Facultad de Ingeniería e Informática; Argentina.Fil: Giovannini, Mirtha E.. Universidad Católica de Salta. Facultad de Ingeniería e Informática; Argentina

10 MeV proton irradiation effects on GaInP/GaAs/Ge concentrator solar cells and their component subcells

In this paper, the experimental results of a 10 MeV proton irradiation on concentrator GaInP/GaAs/Ge lattice-matched triple-junction solar cells and their corresponding subcells are examined. Electro-optical characterization such as external quantum efficiency, light and dark I-V measurements, is performed together with theoretical device modeling in order to guide the analysis of the degradation behavior. The GaInP (on Ge) and Ge cell showed a power loss between beginning of life and end of life of about 4% while the GaInP/GaAs/Ge and GaAs solar cells exhibited the highest damage measured of 12% and 10%, respectively for an irradiation fluence equivalent to an 8-years satellite mission in Low Earth Orbit. The results from single-junction solar cells correlate well with those of triple-junction solar cells. The performance of concentrator solar cells structures is similar to that of traditional space-targeted designs reported in literature suggesting that no special changes may be required to use triple junction concentrator solar cells in space.Fil: Ochoa, M.. Universidad Politécnica de Madrid; EspañaFil: Yaccuzzi, Exequiel Eliseo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; ArgentinaFil: Espinet González, P.. Universidad Politécnica de Madrid; EspañaFil: Barrera, Marcela Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; ArgentinaFil: Barrigón, E.. Universidad Politécnica de Madrid; EspañaFil: Ibarra, María Luján. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; ArgentinaFil: Contreras, Yedileth. Universidad Politécnica de Madrid; EspañaFil: Garcia, Javier. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; ArgentinaFil: López, E.. Universidad Politécnica de Madrid; EspañaFil: Alurralde, M.. Comisión Nacional de Energía Atómica; ArgentinaFil: Algora, C.. Universidad Politécnica de Madrid; EspañaFil: Godfrin, E.. Comisión Nacional de Energía Atómica; ArgentinaFil: Rey Stolle, I.. Universidad Politécnica de Madrid; EspañaFil: Plá, J.. Comisión Nacional de Energía Atómica; Argentina. Universidad Nacional de San Martín; Argentin

10 MeV proton irradiation effects on GaInP/GaAs/Ge concentrator solar cells and their component subcells

In this paper, the experimental results of a 10 MeV proton irradiation on concentrator GaInP/GaAs/Ge lattice-matched triple-junction solar cells and their corresponding subcells are examined. Electro-optical characterization such as external quantum efficiency, light and dark I-V measurements, is performed together with theoretical device modeling in order to guide the analysis of the degradation behavior. The GaInP (on Ge) and Ge cell showed a power loss between beginning of life and end of life of about 4% while the GaInP/GaAs/Ge and GaAs solar cells exhibited the highest damage measured of 12% and 10%, respectively for an irradiation fluence equivalent to an 8-years satellite mission in Low Earth Orbit. The results from single-junction solar cells correlate well with those of triple-junction solar cells. The performance of concentrator solar cells structures is similar to that of traditional space-targeted designs reported in literature suggesting that no special changes may be required to use triple junction concentrator solar cells in space. © 2016 Elsevier B.V