Case study in failure analysis of accelerated life tests (ALT) on III-V commercial triple-junction concentrator solar cells

In this work the failure analysis carried out in III-V concentrator multijunction solar cells after a temperature accelerated life test is presented. All the failures appeared have been catastrophic since all the solar cells turned into low shunt resistances. A case study in failure analysis based on characterization by optical microscope, SEM, EDX, EQE and XPS is presented in this paper, revealing metal deterioration in the bus bar and fingers as well as cracks in the semiconductor structure beneath or next to the bus bar. In fact, in regions far from the bus bar the semiconductor structure seems not to be damaged. SEM images have dismissed the presence of metal spikes inside the solar cell structure. Therefore, we think that for these particular solar cells, failures appear mainly as a consequence of a deficient electrolytic growth of the front metallization which also results in failures in the semiconductor structure close to the bus bars

Inflencia del medio ambiente sobre la casa popular

En número dedicado a: La Vera (Cáceres

Arquitetura gallega en León: Las pallozas

En número dedicado a: León: El Bierzo y Vallegord

EL VANGUARDISMO: MÁS QUE UN MOVIMIENTO LITERARIO

En toda Europa, a partir de 1910, empiezan a desarrollarse unas concepciones artísticas renovadoras y fuertemente iconoclastas cuyo auge será alcanzado en el llamado período entreguerras. Este cambio se da en todas las dimensiones del hacer y pensar; entenderíamos sólo a medias lo que significó el vanguardismo si no nos diéramos cuenta de que en todo lo demás supuso un intento de borrón y cuenta nueva: en la ciencia física, en la arquitectura, pintura, escultura, en la sociedad y en la conciencia literaria.vanguardismo, movimiento literario, Europa

Failure analysis on lattice matched GaInP/Ga(In)As/Ge commercial concentrator solar cells after temperature accelerated life tests

Accelerated life tests are frequently used to provide reliability information in a moderate period of time (weeks or months), and after that, a failure analysis is compulsory to detect the failure origins. In this paper, a failure analysis has been carried out after a temperature accelerated life test on lattice matched GaInP/Ga(In)As/Ge triple junction commercial solar cells. Solar cells were forward biased in darkness inside three climatic chambers in order to emulate the photo-generated current under nominal working conditions (a concentration level of 820 suns). After the accelerated aging test, a characterization of the resulting cells by means of quantum efficiency, dark and illumination I?V curves, electroluminescence, scanning electron microscope, energy dispersive X-ray, scanning transmission electron microscope and X-ray photoelectron spectroscopy has been carried out. Current is identified as the cause of degradation while temperature just dominates the accelerating factor of the aging test. Current promotes the front metal damage produced by the chemical evolution of the electroplating impurities together with those of the tab soldering process. Semiconductor structure does not seem to be responsible of any failure. Therefore, this kind of lattice matched GaInP/Ga(In)As/Ge triple junction solar cells, that as of 2016, are the workhorse of CPV technology, exhibits as a very robust device if the front metal connection is properly accomplished

Characterization of the interface between highly conductive Ga:ZnO films and the silicon substrate

Gallium-doped zinc oxide films are an interesting alternative for transparent conductive materials. To improve their performance, the interface between the grown layer and the substrate must be fully understood. Accordingly, ZnO and Ga:ZnO films have been deposited onto p-type doped Si (111) substrates by magnetron sputtering for 1, 2, 3 and 20 min and their interfaces characterized by transmission electron microscopy, photoelectron spectroscopy, spectroscopic ellipsometry and impedance spectroscopy. The combination of transmission electron microscopy techniques suggested a more complex interface chemistry in the Ga:ZnO/Si case, a point confirmed by x-ray photoelectron spectroscopy measurements on very thin films. While the ZnO/Si interface consists mostly of silicon oxides, zinc silicates and some Zn0, the Ga:ZnO/Si interface, besides these constituents, has a noticeable amount of Ga:ZnO and small quantities of Ga0. The band alignment deduced from the photoelectron spectroscopy measurements, together with the layers and Si band gap values, evidences a higher work function for the doped film and a smaller conduction band barrier for the Ga:ZnO/Si interface. Concerning the optical and electrical characteristics, spectroscopic ellipsometry revealed no significant differences between the two interfaces, while impedance spectroscopy measurements demonstrated that the Ga:ZnO/Si interface is less resistive than the ZnO/Si one.Authors gratefully acknowledge financial support from the Spanish Ministerio de Economía & Competitividad (MINECO) and E.U. FEDER funds through the projects FUNCOAT-CSD2008-00023-CONSOLIDER INGENIO, TEC2014-53906-R, TEC2014-54260-C3-3-P, RYC-2010-06711 and MAT2014-57547-R, and from the Junta de Andalucía (FQM-192)

Integración del centro educativo en el entorno

El proyecto recoge actividades encaminadas a favorecer la relación entre el centro educativo y el entorno y entre las distintas nacionalidades que conviven en la zona. Sus objetivos son lograr la plena integración de los alumnos en su contexto social y natural interrelacionado con su contexto escolar; respetar y valorar la diversidad lingüística y cultural de la zona; y fomentar principios de tolerancia y concordia entre los miembros de la comunidad educativa. Entre las actividades, destacan la elaboración de una guía turística audiovisual de Villa del Prado, y las unidades didácticas La marginación social; Desde la locomotora a la bicicleta de montaña, desde un enfoque natural; Estudio para la construcción y explotación de un invernadero; Paseo urbanístico por Villa del Prado; Los sonidos que nos rodean, la música popular en Villa del Prado; Aldea del Fresno y su entorno, el valor del silencio. La metodología es participativa e integradora, y busca tanto el trabajo personal como en equipo. Se elaboran materiales, como un CD-ROM del Departamento de Música, casete con canciones populares recogidas por los alumnos, trabajos realizados por el alumnado, y CD-ROM con películas y reportaje fotográfico sobre la visita a los invernaderos.Madrid (Comunidad Autónoma). Consejería de EducaciónMadridMadrid (Comunidad Autónoma). Subdirección General de Formación del Profesorado. CRIF Las Acacias; General Ricardos 179 - 28025 Madrid; Tel. + 34915250893ES

Efectividad de los glucocorticoides en pacientes hospitalizados por neumonía grave por SARS-CoV-2

Several studies have reported the beneficial effect of glucocorticoids in the treatment of cytokine storm that occurs in patients with severe COVID-19. Various glucocorticoids regimens have been proposed. Methods Retrospective observational study that includes patients with severe SARS-CoV-2 pneumonia and compares admission to an Intensive Care Unit (ICU) or death during hospitalization in three groups of patients: no glucocorticoids treatment, use of glucocorticoids doses equivalent to less than 250 mg of prednisone daily and use of equivalent doses greater than or equal to 250 mg of prednisone daily. Multivariate analysis was performed using logistic regression, using the propensity index as a covariant. Results Of the 259 patients enrolled in the study, 67 (25.9%) had an unfavorable evolution, dying or requiring ICU admission. Comparative analyzes between different glucocorticoids treatments and the association with ICU admission or death were: glucocorticoids treatment (any dose) versus no glucocorticoids treatment (OR: 0.71 [0.30–1.66]), treatment with glucocorticoids (≥250 mg prednisone daily) versus no glucocorticoids treatment (OR: 0.35 [0.11–1.08]) and glucocorticoids treatment (≥250 mg prednisone daily) versus patients with glucocorticoids doses <250 mg prednisone daily or without glucocorticoids treatment (OR: 0.30 [0.10–0.88]). Conclusion The results of this study show that patients with severe SARS-CoV-2 pneumonia treated with glucocorticoids pulses with equivalent doses of prednisone greater than or equal to 250 mg have a more favorable evolution (less mortality and less admission to ICU).Sin financiación3.200 JCR (2021) Q2, 75/172 Medicine, General & Internal0.325 SJR (2021) Q3, 1635/2489 Medicine (miscellaneous)No data IDR 2020UE