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24. Effects of photon reabsorption phenomena in confocal micro-photoluminescence measurements in crystalline silicon.

Author

Roigé, A., Alvarez, J., Jaffré, A., Desrues, T., Muñoz, D., Martín, I., Alcubilla, R., and Kleider, J.-P.

Subjects
LIGHT absorption, ELECTROMAGNETIC wave absorption, PHOTOLUMINESCENCE measurement, SILICON crystallography, PHOTOVOLTAIC effect
Abstract

Confocal micro-photoluminescence (PL) spectroscopy has become a powerful characterization technique for studying novel photovoltaic (PV) materials and structures at the micrometer level. In this work, we present a comprehensive study about the effects and implications of photon reabsorption phenomena on confocal micro-PL measurements in crystalline silicon (c-Si), the workhorse material of the PV industry. First, supported by theoretical calculations, we show that the level of reabsorption is intrinsically linked to the selected experimental parameters, i.e., focusing lens, pinhole aperture, and excitation wavelength, as they define the spatial extension of the confocal detection volume, and therefore, the effective photon traveling distance before collection. Second, we also show that certain sample properties such as the reflectance and/or the surface recombination velocity can also have a relevant impact on reabsorption. Due to the direct relationship between the reabsorption level and the spectral line shape of the resulting PL emission signal, reabsorption phenomena play a paramount role in certain types of micro-PL measurements. This is demonstrated by means of two practical and current examples studied using confocal PL, namely, the estimation of doping densities in c-Si and the study of back-surface and/or back-contacted Si devices such as interdigitated back contact solar cells, where reabsorption processes should be taken into account for the proper interpretation and quantification of the obtained PL data. [ABSTRACT FROM AUTHOR]

Published
2017
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25. Crystalline silicon surface passivation with amorphous SiC(sub x): H films deposited by plasma-enhanced chemical-vapor deposition

Author

Martin, I., Vetter, M., Garin, M., Orpella, A., Voz, C., Alcubilla, R., and Puigdollers, J.

Subjects
Chemical vapor deposition -- Methods, Silicon carbide -- Atomic properties, Amorphous semiconductors -- Atomic properties, Physics
Abstract

Surface-passivating properties of hydrogenated amorphous silicon carbide films deposited by plasma-enhanced chemical-vapor deposition on both p-and n-type crystalline silicon are extensively studied. The dependence of surface passivation on film deposition conditions is revised including intrinsic a-SiC(sub x):H films on both p-and n-type c-Si and phosphorous-doped a -SiC(sub x): H films on p-type c-Si.

Published
2005

31. Analysis of conduction mechanisms in annealed n-Si(sub 1-x)Cx:H/p-crystalline Si heterojunction diodes for different doping concentrations

Author

Marsal, L.F., Pallares, J., Correig, X., Orpella, A., Bardes, D., and Alcubilla, R.

Subjects
Silicon diodes -- Research, Metallic glasses -- Research, Semiconductor doping -- Research, Physics
Abstract

The transport mechanisms in n-type annealed amorphous Si(sub 1-x)Cx/p-type crystalline Si heterojunctions for three different concentrations are investigated. It is shown that diodes with low doping concentration are the best since the phosphorous slightly diffuses into the crystalline silicon. On the other hand, multitunneling capture emission dominates high doping concentrations. Increased base acceptor doping concentrations also lead to excess current and increased leakage reverse current.

Published
1999

34. Distribution of recombination currents in the space charge region of heterostructure bipolar devices

Author

Pallares, J., Marsal, L.F., Correig, X., Calderer, J., and Alcubilla, R.

Subjects
Semiconductors -- Research, Junction transistors -- Research, Bipolar transistors -- Research, Business, Electronics, Electronics and electrical industries
Abstract

Semiconductor device modeling research has established a design that reduces space charge region Shockley-Read-Hall (SRH) recombination currents to a minimum level. The design is applied to an amorphous/crystalline semiconductor heterojunctions with one noncrystalline side. SRH currents were calculated and applied to the heterojunction technology.

Published
1998

39. Thermal Emission of Silicon at Near-Infrared Frequencies Mediated by Mie Resonances

Author

Universitat Politècnica de València. Centro de Tecnologías Físicas: Acústica, Materiales y Astrofísica - Centre de Tecnologies Físiques: Acústica, Materials i Astrofísica, Universitat Politècnica de València. Instituto Universitario Mixto de Tecnología Química - Institut Universitari Mixt de Tecnologia Química, European Regional Development Fund, Ministerio de Economía y Competitividad, Agencia Estatal de Investigación, Fenollosa Esteve, Roberto, Ramiro-Manzano, Fernando, GARÍN ESCRIVÁ, MOISÉS, Alcubilla, R., Universitat Politècnica de València. Centro de Tecnologías Físicas: Acústica, Materiales y Astrofísica - Centre de Tecnologies Físiques: Acústica, Materials i Astrofísica, Universitat Politècnica de València. Instituto Universitario Mixto de Tecnología Química - Institut Universitari Mixt de Tecnologia Química, European Regional Development Fund, Ministerio de Economía y Competitividad, Agencia Estatal de Investigación, Fenollosa Esteve, Roberto, Ramiro-Manzano, Fernando, GARÍN ESCRIVÁ, MOISÉS, and Alcubilla, R.

Abstract

[EN] Planck's law constitutes one of the cornerstones in physics. It explains the well-known spectrum of an ideal blackbody consisting of a smooth curve, whose peak wavelength and intensity depend on the temperature of the body. This scenario changes drastically, however, when the size of the emitting object is comparable to the wavelength of the emitted radiation. Here we show that a silicon microsphere (2-3 mu m in diameter) heated to around 800 degrees C yields a thermal emission spectrum consisting of pronounced peaks that are associated with Mie resonances. We experimentally demonstrate in the near-infrared the existence of modes with an ultrahigh quality factor, Q, of 400, which is substantially higher than values reported so far, and set a new benchmark in the field of thermal emission. Simulations predict that the thermal response of the microspheres is very fast, about 15 mu s. Additionally, the possibility of achieving light emission above the Planck limit at some frequency ranges is envisaged.

Published
2019

46. Transport mechanisms in silicon heterojunction solar cells with molybdenum oxide as a hole transport layer

Author

García Hernansanz, Rodrigo, García Hemme, Eric, Montero Álvarez, Daniel, Olea Ariza, Javier, Prado Millán, Álvaro del, Mártil de la Plaza, Ignacio, Voz Sánchez, Cristobal, Gerling, Luis, Puigdollers, Joaquin, Alcubilla, R., García Hernansanz, Rodrigo, García Hemme, Eric, Montero Álvarez, Daniel, Olea Ariza, Javier, Prado Millán, Álvaro del, Mártil de la Plaza, Ignacio, Voz Sánchez, Cristobal, Gerling, Luis, Puigdollers, Joaquin, and Alcubilla, R.

Abstract

© 2018 Elsevier B.V. All rights reserved. Authors would like to acknowledge the CAI de Técnicas Físicas of the Universidad Complutense de Madrid for the use of its laboratories. This work was partially supported by the Project MADRID-PV (Grant No. 2013/MAE-2780) funded by the Comunidad de Madrid, by the Spanish MINECO (Ministerio de Economía y Competitividad) under grants TEC 2013-41730-R, TEC2017-84378-R and ENE2016-78933-C4-1-R. Also by the Universidad Complutense de Madrid (Programa de Financiación de Grupos de Investigación UCM–Banco Santander) under grant 910173-2014. D. Montero acknowledges the Spanish MINECO (Ministerio de Economía y Competitividad) for financial support under contract BES-2014-067585and L.G. Gerling the support from Mexico's grant program CONACyT., Heterojunction solar cells based on molybdenum sub-oxide (MoOx) deposited on n-type crystalline silicon have been fabricated. The hole selective character of MoOx is explained by its high workfunction, which causes a strong band bending in the Si substrate. This bending pushes the surface into inversion. In addition, the sub-stoichiometry of the evaporated MoOx layers leads to a high density of states within the bandgap. This is crucial for charge transport. The J-V electrical characteristics at several temperatures were analysed to elucidate the dominant charge transport mechanisms of this heterojunction structure. We have identified two different transport mechanisms. At low bias voltage, transport is dominated by hole tunnelling through the MoOx gap states. At higher voltage the behaviour is similar to a Schottky junction with a high barrier value, due to the high MoOx work function. These results provide a better understanding of the hole selective character of MoOx/n-type silicon heterocontacts, which is key to further improve this new kind of solar cells., Ministerio de Economía y Competitividad (MINECO), Comunidad de Madrid, Universidad Complutense de Madrid/Banco de Santander, Mexico's grant program CONACyT, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

Published
2018

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