Dpto. Física de la Materia Condensada, Cristalografía y Mineralogía - Capítulos de monografías https://uvadoc.uva.es/handle/10324/1243 2026-04-09T09:53:25Z 2026-04-09T09:53:25Z Sanchez, Luis Alberto Moretón Fernández, Ángel Jiménez Martín, Marta María Rodríguez Conde, Sofía Guada, Miguel González Rebollo, Miguel Ángel Martínez Sacristán, Óscar Jiménez López, Juan Ignacio https://uvadoc.uva.es/handle/10324/52900 2023-06-06T12:10:21Z 2018-01-01T00:00:00Z

There is an increasing demand for characterizing multicrystalline solar cells at different stages of its service life. Luminescence techniques, e.g. electroluminescence (EL) and photoluminescence (PL), have acquired a paramount interest in the last years. These techniques are used in imaging mode, allowing to take a luminescence picture at a full wafer/cell scale. This imaging approach is fast and sensitive, but has a low spatial resolution, which avoids a detailed analysis of the defect distribution, which can led to misinterpretations about critical parameters as the minority carrier diffusion length, or the internal and external quantum efficiencies. If one complements these techniques with high spatial resolution techniques, such as light beam induced current (LBIC), one can study the electrical activity of the defects at a micrometric scale, providing additional understanding about the role played by the defects in full wafer/cell luminescence images. The combination of the macroscopic and microscopic resolution scales is necessary for the analysis of the full luminescence images in mc-Si solar cells.

2018-01-01T00:00:00Z Gallardo Saavedra, Sara Moretón Fernández, Ángel Jiménez Martín, Marta María Alonso Gómez, Víctor Hernández Callejo, Luis Martínez Sacristán, Óscar González Rebollo, Miguel Ángel Morales Aragones, José Ignacio https://uvadoc.uva.es/handle/10324/52886 2025-01-31T08:00:25Z 2019-01-01T00:00:00Z

Different techniques can be used to detect and quantify PV modules anomalies, as visual inspections, electrical tests like the I-V curve test, infrared thermography (IRT) or electroluminescence (EL). PV plants operators usually apply only one or two of them within the Operation and Maintenance (O&M) activities. Additionally, researchers usually studied them separately. However, these methods provide complementary results, glimpsing interesting information about the PV site state. The main strength of the research performed is the simultaneous study of all these inspection techniques, studying the correlation between them. Results confirm that, EL and IRT under current injection on modules are closely correlated, while IRT under normal operation (sun exposure) reveals complementary information not detected in EL but existing in the visible spectrum. In conclusion, it is advisable using as many techniques as possible to characterize the actual state of the module and to explain its I-V curve.

2019-01-01T00:00:00Z Moretón Fernández, Ángel Gallardo Saavedra, Sara Jiménez Martín, Marta María Alonso Gómez, Víctor Hernández Callejo, Luis Morales Aragones, José Ignacio Martínez Sacristán, Óscar González Rebollo, Miguel Ángel Jiménez López, Juan Ignacio https://uvadoc.uva.es/handle/10324/52885 2025-01-31T08:04:56Z 2019-01-01T00:00:00Z

Nowadays, electroluminescence imaging (Eli) appears as an emerging technique in the maintenance of photovoltaic (PV) plants. There is a concern about how the current injection needed in ELi measurements can affect the PV modules service life, and how these periodical inspections can affect the long term life of the modules. In order to give a practical answer to this problem, a series of tests consisting of long periods of current injection on several monocrystalline silicon modules has been carried out. The modules tested had already fulfilled their useful life and present multiple defects. In order to analyze how the current injection affects the state of the module, images of infrared thermography (IRT) and ELi were acquired during the current injection period. The subsequent analysis of these images shows only a small effect during the heating period in the EL intensity results at the beginning of each test, not affecting the module performance.

2019-01-01T00:00:00Z Sánchez, L.A. Moretón Fernández, Ángel Guada, Miguel Rodríguez Conde, Sofía Martínez Sacristán, Óscar Jiménez López, Juan Ignacio https://uvadoc.uva.es/handle/10324/31333 2025-03-26T19:45:07Z 2018-01-01T00:00:00Z

Upgraded metallurgical-grade silicon (UMG Si) solar cells with different ranges of efficiencies were characterized through electroluminescence imaging (ELi) and light-beam induced current (LBIC) measurements. The results showed a good correlation between the EL intensity and the efficiency of the solar cells. ELi images gave a bright contrast at the defects, grain boundaries and intragrain defects, and dark contrast inside the grain bodies. Metallic impurities are much more present in some cells due to the directional solidification of the Si ingot. Local short-circuit current mapping with LBIC measurements revealed a bright zone in the neighborhoods of the defects due to the depletion of impurities. Internal quantum efficiencies (IQE) and effective diffusion lengths (Leff) were calculated using different excitation wavelengths. High resolution LBIC measurements revealed micrometric clusters of impurities around intragrain defects

2018-01-01T00:00:00Z Navarro, A. Martínez Sacristán, Óscar Galiana, Beatriz Lombardero, I. Ochoa, M. García, I. Gabás, M. Ballesteros, Carmen Jiménez López, Juan Ignacio Algora, C. https://uvadoc.uva.es/handle/10324/31326 2025-03-26T19:45:06Z 2018-01-01T00:00:00Z

The effects of ex situ annealing in N ambient and in situ annealing in As ambient on GaNSbAs/GaAs structures grown by molecular beam epitaxy were investigated by low temperature cross-sectional cathodoluminescence (CL). The amount and distribution of Sb was measured by energy dispersive spectroscopy (EDS). The cross-sectional CL analysis of all samples reveals a shift of the near band edge (NBE) emission along the growth axis, presumably associated with a non-uniform incorporation of Sb during the growth process, in agreement with the Sb distribution measured by EDS in the as-grown sample. The NBE emission in the annealed samples presents a redshift with respect to the as-grown sample. This effect might be explained by a redistribution/activation of N in the GaNSbAs lattice since the Sb distribution measured by EDS does not reveal significant changes, within the error margin, with respect to the as-grown sample. The in situ annealed in the As overpressure sample shows the best properties for solar cells applications, i.e., a NBE peak position close to 1.0 eV and the lowest full width at half maximum of this emission.

2018-01-01T00:00:00Z Pura Ruiz, José Luis Souto Bartolomé, Jorge Manuel Periwal, Priyanka Baron, Thierry Jiménez López, Juan Ignacio https://uvadoc.uva.es/handle/10324/31324 2021-06-23T10:20:33Z 2018-01-01T00:00:00Z

Semiconductor nanowires are the building blocks of future nanoelectronic devices. The study of the interaction between nanowires and visible light reveals resonances that promise light absorption/scattering engineering for photonic applications. We carried out experimental measurements through the micro-Raman spectroscopy of different group IV nanowires, both homogeneous Si nanowires and axially heterostructured SiGe/Si nanowires. These experimental measurements show an enhancement of the Raman signal in the vicinity of the heterojunction of SiGe/Si nanowires. The results are analysed in terms of the electromagnetic modelling of the light/nanowire interaction using finite element methods. The presence of axial heterostructures is shown to produce electromagnetic resonances, and the results are understood as a consequence of a finite change in the relative permittivity of the material at the SiGe/Si heterojunction. This effect opens a path to controlling interactions between light and matter at the nanoscale with direct applications in photonic nanodevices.

2018-01-01T00:00:00Z Sánchez, L.A. Moretón Fernández, Ángel Guada, Miguel Rodríguez Conde, Sofía Martínez Sacristán, Óscar González Rebollo, Miguel Ángel Jiménez López, Juan Ignacio https://uvadoc.uva.es/handle/10324/31321 2025-03-26T19:45:06Z 2018-01-01T00:00:00Z

Today’s photovoltaic market is dominated by multicrystalline silicon (mc-Si) based solar cells with around 70% of worldwide production. In order to improve the quality of the Si material, a proper characterization of the electrical activity in mc-Si solar cells is essential. A full-wafer characterization technique such as photoluminescence imaging (PLi) provides a fast inspection of the wafer defects, though at the expense of the spatial resolution. On the other hand, a study of the defects at a microscopic scale can be achieved through the light-beam induced current technique. The combination of these macroscopic and microscopic resolution techniques allows a detailed study of the electrical activity of defects in mc-Si solar cells. In this work, upgraded metallurgical grade Si solar cells are studied using these two techniques.

2018-01-01T00:00:00Z Daza, Raquel Gázquez, Fernando Miller, Ana Zelia Sáiz Jiménez, Cesáreo Calaforra, José María Forti, Paolo Rull Pérez, Fernando Medina García, Jesús Sanz Arranz, José Aurelio Martínez Frías, Jesús Toulkeridis, Theofilos https://uvadoc.uva.es/handle/10324/22997 2025-01-09T10:25:01Z 2016-01-01T00:00:00Z

Different types of hard and soft speleothems (stalactites, stalagmites, columns, crusts, flowstones, micro-gours and botryoidal coralloids) have been observed throughout lava tubes in the Galapagos archipelago, Ecuador. Three lava tubes were studied in this work: Gallardo and Royal Palm volcanic caves (Santa Cruz Island) and Sucre Cave (Isabela Island). The studied speleothems were mainly formed by opal, calcite and clay minerals, including plagioclase and pyroxenes from the basaltic host rock. Rarely, iron oxides, gypsum were found in some speleothems, which were interpreted as alteration products of the primary volcanic materials. Field emission scanning electron microscopy revealed abundant filamentous 17th International Vulcanspeleology Symposium 2 bacteria, and reticulated filaments similar to those recently observed in others lava tubes around the world. These filaments are associated with EPS and mineral deposits rich in Si, Ca or Fe. The identified minerals and the evidence of biosignatures suggest a biological contribution to speleothem development within Gallardo, Royal Palm and Sucre lava tubes.

2016-01-01T00:00:00Z