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Microwave annealing (MWA) processes were used for the first time to obtain Ti supersaturated Si. High Ti doses were ion implanted on Si substrates and subsequently MWA processed to recrystallize the amorphous layer. The resulting layers were monocrystalline with a high density of defects. Ti depth profiles indicate that diffusion is avoided once recrystallization is produced. Finally, the electronic transport properties measurements point to a decoupling effect between the Si:Ti layer and the substrate. The implanted layer present also a shallow donor and very high Hall mobility., Universidad Complutense de Madrid, European Regional Development Fund (Unión Europea), Ministerio de Ciencia e Innovación (España), European Social Found (Unión Europea), Ministry of Education (Arabia Saudita), Consejo Nacional de Humanidades, Ciencias y Tecnologías (México), Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

In this article, we study the effect of the inversion charge ( Q _inv ) in a solar cell based on the hole-selective characteristic of substoichiometric molybdenum oxide (MoO_x ) and vanadium oxide (VO_x ) deposited directly on n-type silicon. We measure the capacitance–voltage ( C – V ) curves of the solar cells at different frequencies and explain the results taking into account the variation of the space charge and the existence of Q_inv in the c-Si inverted region. The high-frequency capacitance measurements follow the Schottky metal–semiconductor theory, pointing to a low inversion charge influence in these measurements. However, for frequencies lower than 20 kHz, an increase in the capacitance is observed, which we relate to the contribution of the inversion charge. In addition, applying the metal–semiconductor theory to the high-frequency measurements, we have obtained the built-in voltage potential and show new evidence about the nature of the conduction process in this structure. This article provides a better understanding of the transition metal oxide/n-type crystalline silicon heterocontact., Comunidad de Madrid, Fondo Europeo de Desarrollo Regional (Unión Europea), Ministerio de Ciencia e Innovación (España), Agencia Estatal de Investigación (España), European Social Fund (Unión Europea), Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

Hyperdoped or supersaturated semiconductors are gathering the attention of industry and research institutions due to their sub-bandgap photon absorption properties. In this study, two fast and non-invasive techniques, time-resolved reflectometry (TRR) and Haze Measurements, are applied to infer the melt and solidification regimes of Ti supersaturated 300 mm silicon wafers, aiming to ease the characterization process towards high volume manufacturing of supersaturated materials. Ti supersaturation is attained by using an ion implantation process with a dose 3 x 10(15) cm(-2), which amorphizes the surface. Crystalline quality is then recovered by means of a XeCl UV nanosecond laser annealing process. TRR technique is used to determine two different melting and solidification processes of the laser annealed implanted surface. A first brief, low temperature peak (alpha peak) is associated with the melting process of the amorphized surface, followed by a longer peak/plateau (beta (1) peak/plateau), linked to the melting process of the crystalline phase below the amorphized layer, at sufficiently high laser fluences. Haze technique is used to indirectly measure the crystalline quality after the solidification process of the laser-annealed surface. Atomic force microscopy measurements are used to obtain the surface roughness value and cross-section high resolution transmission electron microscopy micrographs to check crystalline quality., Ministerio de Ciencia e Innovación (España), Comunidad de Madrid, Ministerio de Economia y Competitividad (España), Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2023 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works., In this article, we study the effect of the inversion charge ( Q inv ) in a solar cell based on the hole-selective characteristic of substoichiometric molybdenum oxide (MoO x ) and vanadium oxide (VO x ) deposited directly on n-type silicon. We measure the capacitance–voltage ( C – V ) curves of the solar cells at different frequencies and explain the results taking into account the variation of the space charge and the existence of Q inv in the c-Si inverted region. The high-frequency capacitance measurements follow the Schottky metal–semiconductor theory, pointing to a low inversion charge influence in these measurements. However, for frequencies lower than 20 kHz, an increase in the capacitance is observed, which we relate to the contribution of the inversion charge. In addition, applying the metal–semiconductor theory to the high-frequency measurements, we have obtained the built-in voltage potential and show new evidence about the nature of the conduction process in this structure. This article provides a better understanding of the transition metal oxide/n-type crystalline silicon heterocontact., The authors would like to acknowledge the CAI de Técnicas Físicas of the Universidad Complutense de Madrid. The authors would also like to thank the Mexican grants program CONACyT for its financial collaboration., Peer Reviewed, Postprint (author's final draft)

Artículo firmado por 15 autores. © 2022 IOP Publishing Ltd. The authors would like to thank the Physical Sciences Research Assistance Centre (CAI de Técnicas Físicas) of the Complutense University of Madrid. This study was partially funded by Project MADRID-PV2 (P2018/EMT-4308), with aid from the Regional Government of Madrid and the ERDF, by the Spanish Ministry of Science and Innovation/National Research Agency (MCIN/AEI) under Grants TEC2017- 84378-R, PID2019-109215RB-C41, PID2020-116508RB-I00 and PID2020-117498RB-I00. Daniel Caudevilla would like to express his thanks for Grant PRE2018-083798, provided by the MICINN and the European Social Fund. Francisco Pérez Zenteno would also like to express his thanks for Grant 984933, provided by CONACyT (Mexico)., According to intermediate band (IB) theory, it is possible to increase the efficiency of a solar cell by boosting its ability to absorb low-energy photons. In this study, we used a hyperdoped semiconductor approach for this theory to create a proof of concept of different silicon-based IB solar cells. Preliminary results show an increase in the external quantum efficiency (EQE) in the silicon sub-bandgap region. This result points to sub-bandgap absorption in silicon having not only a direct application in solar cells but also in other areas such as infrared photodetectors. To establish the transport mechanisms in the hyperdoped semiconductors within a solar cell, we measured the J-V characteristic at different temperatures. We carried out the measurements in both dark and illuminated conditions. To explain the behavior of the measurements, we proposed a new model with three elements for the IB solar cell. This model is similar to the classic two-diodes solar cell model but it is necessary to include a new limiting current element in series with one of the diodes. The proposed model is also compatible with an impurity band formation within silicon bandgap. At high temperatures, the distance between the IB and the n-type amorphous silicon conduction band is close enough and both bands are contacted. As the temperature decreases, the distance between the bands increases and therefore this process becomes more limiting., Project MADRID-PV2, Regional Government of Madrid, ERDF, Spanish Ministry of Science and Innovation/National Research Agency (MCIN/AEI), Ministerio de Ciencia e Innovación, European Social Fund, CONACyT (Mexico), Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2022 IOP Publishing Ltd. Authors wish to acknowledge assistance from CAI de Técnicas Físicas (Unidad de Implantación Iónica) and CAI de Técnicas Químicas (Espectroscopía Raman y Correlación) from the Universidad Complutense de Madrid with the Ion Implantations and Raman measurements, respectively. We also acknowledge Servicio de Nanotecnología y Análisis de Superficies del CACTI de la Universidad de Vigo for ToF-SIMS measurements and ICTS-CNM from Madrid for the SEM images. This work was partially supported by the Projects MADRID-PV2 (P2018/EMT-4308) funded by the Comunidad Autónoma de Madrid with the support from FEDER Funds and Projects SCCell (PID2020-116508RB-I00), HyperPHIR (PID2020-117498RB-I00) and SCALED (PID2019-109215RB-C42), funded by the Spanish Ministry of Science and Innovation. D Caudevilla would also acknowledge the Grant PRE2018-083798, financed by MICINN and European Social Fund. F Pérez-Zenteno would also like to acknowledge Grant 786327 form Mexican grants program CONACyT., In this work we have successfully hyperdoped germanium with tellurium with a concentration peak of 10(21) cm(-3). The resulting hyperdoped layers show good crystallinity and sub-bandgap absorption at room temperature which makes the material a good candidate for a new era of complementary metal-oxide-semiconductor-compatible short-wavelength-infrared photodetectors. We obtained absorption coefficients ci higher than 4.1 x 10(3) cm(-1) at least up to 3 mu m. In this study we report the temperature-dependency electrical properties of the hyperdoped layer measured in van der Pauw configuration. The electrical behaviour of this hyperdoped material can be explained with an electrical bilayer coupling/decoupling model and the values for the isolated hyperdoped layer are a resistivity of 4.25 x 10(-3) Omega.cm with an electron-mobility around -100 cm(2) V-1 s(-1)., Ministerio de Ciencia e innovación (MICINN)., Ministerio de Ciencia e Innovación (MICINN)/FEDER, Comunidad de Madrid/ FEDER, Mexican grants program CONACyT, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

CRUE-CSIC (Acuerdos Transformativos 2021) The authors acknowledge the "CAI de Tecnicas Fisicas", the "CAI de Difraccion de Rayos X '' of Universidad Complutense de Madrid, and "Laboratorio de Caracterizacion de Superficies" of CENIM for sample fabrication, GIXRD and XPS measurements, respectively. Also we acknowledge J. Gandia for his support in the analysis of the optical measurements. This work is part of the project MADRID-PV2 (P2018/EMT-4308) funded by the Comunidad Autonoma de Madrid with the support from FEDER Funds, project TEC2017-84378-R, funded by MICINN and European Social Fund, and projects SCCell (PID2020-116508RB-I00) , HyperPHIR (PID2020-117498RB-I00) and SCALED (PID2019-109215RB-C42) , funded by the Spanish Ministry of Science and Innovation. D.Pastor acknowledges financial support from the MEC to the program Ramon y Cajal (No. RYC-2014-16936) . D. Caudevilla would also acknowledge grant PRE2018-083798, financed by MICINN and European Social Fund., This article studies the physical and electrical behavior of indium tin oxide layers (ITO) grown by an unconventional technique: High Pressure Sputtering (HPS), from a ceramic ITO target in a pure Ar atmosphere. This technique has the potential to reduce plasma induced damage to the samples. The aim is to obtain, at low temperature via HPS, good quality transparent conductive oxide layers for experimental photovoltaic cells with emerging selective contacts such as transition metal oxides, alkaline metal fluorides, etc. We found that the resistivity of the films was strongly dependent on Ar pressure. To obtain device-quality resistivity without intentional heating during deposition a pressure higher than 1.0 mbar was needed. These films deposited on glass were amorphous, presented a high electron mobility (up to 45 cm2V- 1s- 1) and a high carrier density (2.9 x 1020 cm-3 for the sample with the highest mobility). The optimum Ar pressure range was found at 1.5-2.3 mbar. However, the resistivity degraded with a moderate annealing temperature in air. Finally, the feasibility of the integration with photovoltaic cells was assessed by depositing on Si substrates passivated by a-Si:H. The film deposited at 1.5 mbar was uniform and amorphous, and the carrier lifetime obtained was 1.22 ms with an implied open circuit voltage of 719 mV after a 215 degrees C air anneal. The antireflective properties of HPS ITO were also demonstrated. These results show that ITO deposited by HPS is adequate for the research of solar cells with emerging selective contacts., Ministerio de Ciencia e Innovación (MICINN)/ESF, Ministerio de Ciencia e Innovación (MICINN), Comunidad de Madrid/FEDER, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

Se deposita la versión posprint del artículo, In the scope of supersaturated semiconductors for infrared detectors, we implanted Si samples with Ti at high doses and processed them by rapid thermal annealing (RTA) to recover the crystal quality. Also, for comparative purposes, some samples were processed by pulsed-laser melting. We measured the electronic transport properties at variable temperatures and analyzed the results. The results indicate that, for RTA samples, surface layers with a high Ti concentration have negligible conductivity due to defects. In contrast, the implantation tail region has measurable conductivity due to very high electron mobility. This region shows the activation of a very shallow donor and a deep donor level. While deep levels have been previously reported for Ti in Si, such a shallow level has never been measured, and we suggest that it originates from Ti-Si complexes. Finally, a decoupling effect between the implanted layer and the substrate seems to be present, and a bilayer model is applied to fit the measured properties. The fitted parameters follow the Meyer–Neldel rule. The role of the implantation tails in Si supersaturated with Ti is revealed in this work., Comunidad de Madrid, ERDF Funds - MICINN, European Social Fund (ESF), Ministerio de Ciencia e Innovación (España), Mexican grants program CONACyT, Ministry of Education in the Kingdom of Saudi Arabia, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

Authors would like to acknowledge the technical and human support provided by Facility of Analysis and Characterization of Solids and Surfaces of SAIUEx (financed by UEX, Junta de Extremadura, MICINN, FEDER and FSE), as well as the CAI de Técnicas Físicas of the Universidad Complutense de Madrid for the ion implantation and rapid thermal annealing processes, and the ICTS Centro Nacional de Microscopia Electrónica for the microstructural measurements. The authors would like to thank Sven Kayser from IONTOF GmbH (Germany) for his helpful discussion about the dual beam configuration and ion beam mixing artefact. This work was partially supported by the Project MADRID-PV2 (P2018/EMT-4308) funded by the Regional Government of Madrid with the support from the European Regional Development Fund (ERDF), by the Spanish MINECO (Ministerio de Economía y Competitividad) under grants TEC2017-84378-R, PID2020-116508RB-I00, and PID2020-117498RB-I00. Daniel Caudevilla would also acknowledge the grant PRE2018-083798, financed by MICINN and European Social Fund. The authors are also thankful for financial collaboration from the Mexican grants program CONACyT., This work deepens the understanding of the optoelectronic mechanisms ruling hyperdoped-based photodevices and shows the potential of Ti hyperdoped-Si as a fully complementary metal-oxide semiconductor compatible material for room-temperature infrared photodetection technologies. By the combination of ion implantation and laser-based methods, approximate to 20 nm thin hyperdoped single-crystal Si layers with a Ti concentration as high as 10(20) cm(-3) are obtained. The Ti hyperdoped Si/p-Si photodiode shows a room temperature rectification factor at +/- 1 V of 509. Analysis of the temperature-dependent current-voltage characteristics shows that the transport is dominated by two mechanisms: a tunnel mechanism at low bias and a recombination process in the space charge region at high bias. A room-temperature sub-bandgap external quantum efficiency (EQE) extending to 2.5 mu m wavelength is obtained. Temperature-dependent spectral photoresponse behavior reveals an increase of the EQE as the temperature decreases, showing a low-energy photoresponse edge at 0.45 eV and a high-energy photoresponse edge at 0.67 eV. Temperature behavior of the open-circuit voltage correlates with the high-energy photoresponse edge. A model is proposed to relate the optoelectronic mechanisms to sub-bandgap optical transitions involving an impurity band. This model is supported by numerical semiconductor device simulations using the SCAPS software., MADRID-PV2 - Regional Government of Madrid, European Regional Development Fund (ERDF), Ministerio de Economía y Competitividad (MINECO), MICINN, European Social Fund, CONACyT, UEX, Junta de Extremadura, FEDER, FSE, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

According to intermediate band (IB) theory, it is possible to increase the efficiency of a solar cell by boosting its ability to absorb low-energy photons. In this study, we used a hyperdoped semiconductor approach for this theory to create a proof of concept of different silicon-based IB solar cells. Preliminary results show an increase in the external quantum efficiency (EQE) in the silicon sub-bandgap region. This result points to sub-bandgap absorption in silicon having not only a direct application in solar cells but also in other areas such as infrared photodetectors. To establish the transport mechanisms in the hyperdoped semiconductors within a solar cell, we measured the J–V characteristic at different temperatures. We carried out the measurements in both dark and illuminated conditions. To explain the behavior of the measurements, we proposed a new model with three elements for the IB solar cell. This model is similar to the classic two-diodes solar cell model but it is necessary to include a new limiting current element in series with one of the diodes. The proposed model is also compatible with an impurity band formation within silicon bandgap. At high temperatures, the distance between the IB and the n-type amorphous silicon conduction band is close enough and both bands are contacted. As the temperature decreases, the distance between the bands increases and therefore this process becomes more limiting., The authors would like to thank the Physical Sciences Research Assistance Centre (CAI de Técnicas Físicas) of the Complutense University of Madrid. This study was partially funded by Project MADRID-PV2 (P2018/EMT-4308), with aid from the Regional Government of Madrid and the ERDF, by the Spanish Ministry of Science and Innovation/National Research Agency (MCIN/AEI) under grants TEC2017- 84378-R, PID2019-109215RB-C41, PID2020-116508RB-I00 and PID2020- 117498RB-I00. Daniel Caudevilla would like to express his thanks for grant PRE2018-083798, provided by the MICINN and the European Social Fund. Francisco Pérez Zenteno would also like to express his thanks for grant 984933, provided by CONACyT (Mexico)., Peer Reviewed, Postprint (author's final draft)

©IEEE. Spanish Conference on Electron Devices (CDE) (13.2021. Sevilla) This work is part of the project TEC2017-84378-R, funded by MICINN and European Social Fund and project MADRID-PV2 (P2018/EMT-4308) funded by the Comunidad Autónoma de Madrid with the support from FEDER Funds. Parts of this research were carried out at IBC at the Helmholtz–Zentrum Dresden–Rossendorf e. V., a member of the Helmholtz Association. Authors would like to thank Ulrich Kentsch for his assistance with the lowtemperature implantations. D. Caudevilla would also acknowledge grant PRE2018-083798, financed by MICINN and European Social Fund. D. Pastor acknowledges financial support from the program Ramón y Cajal (Grant No. RYC2014-16936)., Germanium hyperdoped with deep level donors, such as tellurium, would lead to dopant-mediated sub-band gap mid-infrared photoresponse at room temperature. We use a combination of non-equilibrium techniques to supersaturate Ge with Te via ion implantation followed by pulsed laser melting (PLM). Typically, liquid N2 (77K) temperatures are used to avoid implantation-induced Ge surface porosity. In this work, alternatively, we report on the use of slightly higher implantation temperatures (143 K) together with an amorphous Si (a-Si) capping layer. We demonstrate that the solid solubility limit of Te in Ge is overcome upon recovering the crystallinity of the material after laser processing., Ministerio de Ciencia e Innovación (MICINN), Comunidad de Madrid/FEDER, Programa Ramón y Cajal, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

El proyecto ha consistido en la creación de un espacio virtual en Moodle para publicar contenidos complementarios para las asignaturas relacionadas con el área de la Electrónica.

© 2019 Elsevier B.V. All rights reserved. Authors would like to acknowledge the C.A.I. de Técnicas Físicas of the Universidad Complutense de Madrid for ion implantation and evaporation processes. Also, the Institute for Optoelectronics Systems and Microtechnology of the Universidad Politécnica de Madrid for photoluminescence experiments. The fabrication of TEM samples were conducted in the Laboratorio de Microscopias Avanzadas at the Instituto de Nanociencia de Aragón (LMA-INA) of the Universidad de Zaragoza. Authors acknowledge the LMA-INA for offering access to their instruments and expertise, and the Centro Nacional de Microelectrónica at the Moncloa Campus for the TEM and XEDS measurements. This work was partially supported by the Spanish Ministry of Science, Innovation and Universities under grants TEC2017-84378-R and RTI 2018-096498-B-I00. The work of D. Montero was supported by the Spanish MINECO under contract BES-2014-067585. This work is part of the project MADRID-PV2 P-2018/EMT-4308 funded by the Regional Government of Madrid with the support from FEDER funds., We have fabricated GaP supersaturated with Ti by means of ion implantation and pulsed-laser melting to obtain an intermediate band material with applications in photovoltaics. This material has a strong sheet photoconductance at energies below the bandgap of GaP and it seems to be passivated by a Ga defective GaPO oxide layer during the laser process. Passivation is consistently analyzed by sheet photoconductance and photoluminescence measurements. We report on the structural quality of the resulting layers and analyze the energy of the new optical transitions measured on GaP:Ti. A collapse found in the sheet photoconductance spectra of GaP:Ti samples fabricated on undoped substrates is explained by the negative photoconductivity phenomenon. (C) 2019 Elsevier B.V. All rights reserved., Ministerio de Ciencia e Innovación (MICINN), Ministerio de Economía y Competitividad (MINECO), Comunidad de Madrid/FEDER, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

We will present in this work the design and assembling of a radiofrequency multicathode sputtering system. The system is water refrigerated and its vacuum system is able to reach vacuum in the range 10‾ ⁷ mbar. It is designed for deposition and growth of thin metallic films for ohmic contacts on n- and p-type silicon. The system has been calibrated to use with three different cathodes, which all of them are assembled in the same chamber. The sample holder can be orientated in different positions for facing the targets and also to a blind position for cleaning processes. The targets used in the system are titanium, aluminum and tungsten. To perform the system calibration we have prepared different samples by lithography and we performed profilometry measurements to know the thickness of the deposited material., En este trabajo se detalla el diseno, fabricación y montaje de un sistema de pulverización multicátodo por radiofrecuencia. El sistema está refrigerado por agua y alcanza vacíos del orden de 10‾⁷ mbar. El sistema esta diseñado para depositar y crecer láminas delgadas metálicas contactos ohmicos sobre silicio dopado tipo n y tipo p. El sistema ha sido calibrado para tres blancos diferentes, los cuales se encuentran en la misma cámara. El portamuestras puede orientasre hacia cualquiera de los blancos o en una cuarta posición ciega para procesos de limpieza. Los blancos utilizados en el sistema son titanio, aluminio y wolframio. Para su calibración se han preparado diferentes muestras mediante un proceso de litografía y se han llevado a cabo medidas mediante perfilometría de contacto para conocer el espesor del material depositado.