122 results on '"López-Vidrier, J."'
Search Results
2. Comparison of three titanium-precursors for atomic-layer-deposited TiO2 for passivating contacts on silicon
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Hiller, D., (0000-0003-2506-6869) Munnik, F., López-Vidrier, J., Solonenko, D., Reif, J., Knaut, M., Thimm, O., Grant, N. E., Hiller, D., (0000-0003-2506-6869) Munnik, F., López-Vidrier, J., Solonenko, D., Reif, J., Knaut, M., Thimm, O., and Grant, N. E.
- Abstract
Atomic layer-deposited (ALD) TiO2 thin films on silicon were deposited using titanium tetrachloride (TiCl4), titanium tetraisopropoxide (TTIP), and tetrakis(dimethylamino)titanium (TDMAT) together with water vapor as the oxidant at temperatures ranging between 75 and 250 °C. The Si surface passivation quality of as-deposited and isothermally annealed samples was compared using photoconductance lifetime measurements in order to calculate their effective surface recombination velocities Seff. A low Seff of 3.9 cm/s (J0s = 24 fA/cm2) is achieved for as-deposited TiCl4-TiO2 at 75 °C when a chemically grown (i.e., from RCA cleaning) SiOx interface layer is present. Depositing TTIP-TiO2 at 200 °C on a chemically grown SiOx interface layer yields equivalent Seff values; however, in this case, TTIP-TiO2 requires a 5–15 min postdeposition forming gas anneal at 250 °C. In contrast, TDMAT-TiO2 was not found to provide a similar level of passivation with/without a chemically grown SiOx interface layer and postdeposition anneal. Modeling of the effective lifetime curves was used to determine the magnitude of the effective charge densities Qf in the TiO2 films. In all cases, Qf was found to be of the order of ∼10^11 q cm−2, meaning field-effect passivation arising from ALD TiO2 is relatively weak. By comparing the material properties of the various TiO2 films using ellipsometry, photothermal deflection spectroscopy, Raman spectroscopy, elastic recoil detection analysis, x-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy, we find experimental support for the role of Cl (in conjunction with hydrogen) playing a beneficial role in passivating dangling bond defects at the Si surface. It is concluded that low deposition temperature TiCl4 processes are advantageous, by providing the lowest Seff without any postanneal and a comparatively high growth per cycle (GPC).
- Published
- 2024
3. Activation of visible up-conversion luminescence in transparent and conducting ZnO:Er:Yb films by laser annealing
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Lluscà, M., López-Vidrier, J., Lauzurica, S., Sánchez-Aniorte, M.I., Antony, A., Molpeceres, C., Hernández, S., Garrido, B., and Bertomeu, J.
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- 2015
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4. Up-conversion effect of Er- and Yb-doped ZnO thin films
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Lluscà, M., López-Vidrier, J., Antony, A., Hernández, S., Garrido, B., and Bertomeu, J.
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- 2014
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5. Electro-optical Properties of Non-stoichiometric Silicon Nitride Films for Photovoltaic Applications
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Blázquez, O., López-Vidrier, J., Hernández, S., Montserrat, J., and Garrido, B.
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- 2014
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6. High – Mobility Flourine Doped Indium Oxide Films For high Efficiency Silicon Solar Cells
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Tom, T., Tutsch, L., Hermle, M., Asensi, J.M., López-Vidrier, J., Bertomeu, J., and Bivour, M.
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Low Temperature Route for Si Cells ,Silicon Materials and Cells - Abstract
8th World Conference on Photovoltaic Energy Conversion; 128-132, Transparent conducting oxides with high infrared transparency and high mobility are crucial for further enhancing the efficiency of crystalline silicon solar cells. Numerous hydrogen-doped or cation-doped indium oxide films have been intensively studied, while anion doping in indium oxide films is still under development. Here we investigate the fluorine doped indium oxide films deposited by industrial DC sputtering by varying the oxygen and hydrogen percentages. To gain a holistic understanding on the role of hydrogen and oxygen we performed a very wide parameter variation of these gases. The films were processed at room temperature and were annealed at 220 °C on a hot plate in ambient conditions. Electrical, optical, and structural properties of the films were investigated and highest mobility of 87 cm2/Vs at a carrier density of 2.5×1020 cm−3 was achieved when depositing under 2.3% O2 and 2.0% H2 flow. The strong correlation between the defined figure of merit and the electron mobility of the films is observed. The solid phase crystallization of the annealed films was identified by X-ray diffraction. The highest mobility films achieved an efficiency of 21.8% in silicon heterojunction solar cells..
- Published
- 2022
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7. Pathways of carrier recombination in Si/SiO2 nanocrystal superlattices.
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Chlouba, T., Trojánek, F., Kopecký, V., López-Vidrier, J., Hernandéz, S., Hiller, D., Gutsch, S., Zacharias, M., and Malý, P.
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ELECTRON-hole recombination ,SUPERLATTICES ,PHOTOVOLTAIC cells ,PLASMA sheaths ,SOLAR cells ,AMORPHOUS silicon ,RAMAN spectroscopy - Abstract
We investigated picosecond carrier recombination in Si/SiO
2 nanocrystal superlattices by ultrafast transient transmission, time-resolved photoluminescence, and Raman spectroscopy. The recombination is of multicarrier origin and it depends strongly on the nanoscale structure of the samples (e.g., crystallinity, percolation, and size distribution). Several recombination pathways were found, including Auger recombination, trapped-carrier Auger recombination, exciton–exciton recombination, and subsequent trapping in band tail states of amorphous silicon phase. The sample microscopic structure is determined using a single parameter, the stoichiometric parameter x, during the plasma-enhanced chemical-vapor deposition process. The percolated samples are hot candidates for all-silicon tandem photovoltaic solar cells in the future. [ABSTRACT FROM AUTHOR]- Published
- 2019
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8. Silicon nanocrystals-based electroluminescent resistive switching device.
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Frieiro, J. L., López-Vidrier, J., Blázquez, O., Yazıcıoğlu, D., Gutsch, S., Valenta, J., Hernández, S., Zacharias, M., and Garrido, B.
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ELECTROLUMINESCENT devices , *INTEGRATED circuits , *SILICON , *OPTICAL properties , *RESISTANCE to change - Abstract
In the last few years, the emergence of studies concerning the resistive switching (RS) phenomenon has resulted in the finding of a large amount of materials being capable of acting as an active layer in such devices, i.e., the layer where the change in resistance takes place. Whereas the normal operation consists of the electrical readout of the modified resistance state of the device after electrical writing, electro-photonic approaches seek the involvement of light in these devices, be it either for the active Set or Reset operations or the readout. We propose in this work silicon nanocrystal multilayers (Si NC MLs) as an active material for being used in RS devices, taking advantage of their outstanding optical properties. The resistance states of Si NC MLs were obtained by electrical excitation, whose readout is carried out by electrical and electro-optical means, thanks to a distinguishable electroluminescence emission under each state. To achieve this, we report on an adequate design that combines both the Si NC MLs with ZnO as a transparent conductive oxide, whose material properties ensure the device RS performance while allowing the electro-optical characterization. Overall, such an occurrence states the demonstration of a Si NCs-based electroluminescent RS device, which paves the way for their future integration into photonic integrated circuits. [ABSTRACT FROM AUTHOR]
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- 2019
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9. Elimination of Interface Energy Barriers Using Dendrimer Polyelectrolytes with Fractal Geometry
- Author
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Ros, E., Tom, T., Ortega, P., Martin, I., Maggi, E., Asensi, J. M., López-Vidrier, J., Saucedo, E., Bertomeu, J., Puigdollers, J., and Voz, C.
- Abstract
In this work we study conjugated polyelectrolyte (CPE) films based on polyamidoamine (PAMAM) dendrimers of generations G1 and G3. These fractal macromolecules are compared to branched polyethylenimine (b-PEI) polymer using methanol as the solvent. All of these materials present a high density of amino groups, which protonated by methoxide counter-anions create strong dipolar interfaces. The vacuum level shift associated to these films on n-type silicon was 0.93 eV for b-PEI, 0.72 eV for PAMAM G1 and 1.07 eV for PAMAM G3. These surface potentials were enough to overcome Fermi level pinning, which is a typical limitation of aluminium contacts on n-type silicon. A specific contact resistance as low as 20 mΩ·cm2was achieved with PAMAM G3, in agreement with the higher surface potential of this material. Good electron transport properties were also obtained for the other materials. Proof-of-concept silicon solar cells combining vanadium oxide as a hole-selective contact with these new electron transport layers have been fabricated and compared. The solar cell with PAMAM G3 surpassed 15% conversion efficiency with an overall increase of all the photovoltaic parameters. The performance of these devices correlates with compositional and nanostructural studies of the different CPE films. Particularly, a figure-of-merit (Vσ) for CPE films that considers the number of protonated amino groups per macromolecule has been introduced. The fractal geometry of dendrimers leads to a geometric increase in the number of amino groups per generation. Thus, investigation of dendrimer macromolecules seems a very good strategy to design CPE films with enhanced charge-carrier selectivity.
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- 2023
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10. Structural and optical characterization of size controlled silicon nanocrystals in SiO2/SiOxNy multilayers
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López-Vidrier, J., Hernández, S., Hartel, A.M., Hiller, D., Gutsch, S., Löper, P., López-Conesa, L., Estradé, S., Peiró, F., Zacharias, M., and Garrido, B.
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- 2011
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11. Ultraviolet, visible and near infrared photoresponse of SiO2/Si/SiO2 multilayer system into a MOS capacitor
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González-Flores, K.E., primary, Frieiro, J.L., additional, Horley, P., additional, Pérez-García, S.A., additional, Palacios-Huerta, L., additional, Moreno, M., additional, López-Vidrier, J., additional, Hernández, S., additional, Garrido, B., additional, and Morales-Sánchez, A., additional
- Published
- 2021
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12. Electroforming of Si NCs/p-Si photovoltaic devices: Enhancement of the conversion efficiency through resistive switching
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Frieiro, J.L., primary, López-Vidrier, J., additional, Blázquez, O., additional, Ibáñez, J., additional, Yazıcıoğlu, D., additional, Gutsch, S., additional, Zacharias, M., additional, Garrido, B., additional, and Hernández, S., additional
- Published
- 2021
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13. Structural and High-Pressure Properties of Rheniite (ReS2) and (Re,Mo)S-2
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Ministerio de Ciencia, Innovación y Universidades (España), Ministry of Science and Higher Education (Poland), Ibáñez Insa, Jordi [0000-0002-8909-6541], Ibáñez Insa, Jordi, Woźniak, T., Oliva, Robert, Popescu, C., Hernàndez, Sergi, López-Vidrier, J., Ministerio de Ciencia, Innovación y Universidades (España), Ministry of Science and Higher Education (Poland), Ibáñez Insa, Jordi [0000-0002-8909-6541], Ibáñez Insa, Jordi, Woźniak, T., Oliva, Robert, Popescu, C., Hernàndez, Sergi, and López-Vidrier, J.
- Abstract
Rhenium disulfide (ReS2), known in nature as the mineral rheniite, is a very interesting compound owing to its remarkable fundamental properties and great potential to develop novel device applications. Here we perform density functional theory (DFT) calculations to investigate the structural properties and compression behavior of this compound and also of the (Re,Mo)S-2 solid solution as a function of Re/Mo content. Our theoretical analysis is complemented with high-pressure X-ray diffraction (XRD) measurements, which have allowed us to reevaluate the phase transition pressure and equation of state of 1T-ReS2. We have observed the 1T-to-1T' phase transition at pressures as low as similar to 2 GPa, and we have obtained an experimental bulk modulus, B-0, equal to 46(2) GPa. This value is in good agreement with PBE+D3 calculations, thus confirming the ability of this functional to model the compression behavior of layered transition metal dichalcogenides, provided that van der Waals corrections are taken into account. Our experimental data and analysis confirm the important role played by van der Waals effects in the high-pressure properties of 1T-ReS2.
- Published
- 2021
14. Electroforming of Si NCs/p-Si photovoltaic devices: Enhancement of the conversion efficiency through resistive switching
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Ministerio de Economía, Industria y Competitividad (España), German Research Foundation, Ministerio de Educación, Cultura y Deporte (España), Ibáñez Insa, Jordi [0000-0002-8909-6541], Frieiro, J. L., López-Vidrier, J., Blázquez, O., Ibáñez Insa, Jordi, Yazicioglu, D., Gutsch, S., Zacharias, M., Garrido, B., Hernández, S., Ministerio de Economía, Industria y Competitividad (España), German Research Foundation, Ministerio de Educación, Cultura y Deporte (España), Ibáñez Insa, Jordi [0000-0002-8909-6541], Frieiro, J. L., López-Vidrier, J., Blázquez, O., Ibáñez Insa, Jordi, Yazicioglu, D., Gutsch, S., Zacharias, M., Garrido, B., and Hernández, S.
- Abstract
In this work, the relation between the photovoltaic and resistive switching (RS) properties of metal-oxide-semiconductor devices containing Si nanocrystal (Si NC) superlattices is investigated. A first approximation concludes that the low resistance state achieved by the RS process allows for enhanced photogenerated carrier extraction when compared to the high resistance state and pristine devices. By using different current compliance values during the electroforming process, the low resistance state is further modified, improving its conductivity and the collection probability of photogenerated carriers. Conversion efficiency is enhanced by at least one and up to five orders of magnitude by applying different electroforming processes. In addition to promoting the RS properties in these devices, spectral response measurements demonstrate that Si NCs are partially responsible for the optical absorption, and that their contribution is maintained after electroforming. We thus conclude that the proposed methodology can improve the conversion efficiency of this and other multijunction solar cells or structures that also exhibit RS properties. Through RS, a dense network of conductive filaments is promoted in the insulating region, which reduces the travel distance of photocarriers for their collection.
- Published
- 2021
15. Towards a white LED based on rare earth-doped ZnO
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Frieiro, J, Guillaume, C, López-Vidrier, J, Blázquez, O, González-Torres, S, Labbé, C, Hernández, S, Portier, Xavier, Garrido, B, Department of Electronics and Biomedical Engineering / Departament d'Enginyeria Electrònica i Biomèdica [Spain] (DEBE), Universitat de Barcelona (UB), Institute of Nanoscience and Nanotechnology (IN2UB), Universitat Autònoma de Barcelona (UAB), Nanomatériaux, Ions et Métamatériaux pour la Photonique (NIMPH), Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), and Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)
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Condensed Matter::Materials Science ,[PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci] - Abstract
International audience; By using ZnO thin films doped with Ce, Tb or Eu, deposited via radiofrequency magnetron sputtering, we have developed monochromatic (blue, green and red, respectively) light emitting devices (LEDs). The rare earth ions introduced with doping rates lower than 2% exhibit narrow and intense emission peaks due to electronic transitions in relaxation processes induced after electrical excitation. This study proves zinc oxide to be a good host for these elements, its high conductivity and optical transparency in the visible range being as well exploited as top transparent electrode. After structural characterization of the different doped layers, a device structure with intense electroluminescence is presented, modeled, and electrically and optically characterized. The different emission spectra obtained are compared in a chromatic diagram, providing a reference for future works with similar devices. The results hereby presented demonstrate three operating monochromatic LEDs, as well as a combination of the three species into another one, with a simply-designed structure compatible with current Si technology and demonstrating an integrated red-green-blue emission.
- Published
- 2020
16. Toward RGB LEDs based on rare earth-doped ZnO
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Frieiro, J L, primary, Guillaume, C, additional, López-Vidrier, J, additional, Blázquez, O, additional, González-Torres, S, additional, Labbé, C, additional, Hernández, S, additional, Portier, X, additional, and Garrido, B, additional
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- 2020
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17. Photoelectrical reading in ZnO/Si NCs/p-Si resistive switching devices
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López-Vidrier, J., primary, Frieiro, J. L., additional, Blázquez, O., additional, Yazicioglu, D., additional, Gutsch, S., additional, González-Flores, K. E., additional, Zacharias, M., additional, Hernández, S., additional, and Garrido, B., additional
- Published
- 2020
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18. Light-activated electroforming in ITO/ZnO/p-Si resistive switching devices
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Blázquez, O., primary, Frieiro, J. L., additional, López-Vidrier, J., additional, Guillaume, C., additional, Portier, X., additional, Labbé, C., additional, Hernández, S., additional, and Garrido, B., additional
- Published
- 2019
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19. Size-Controlled Si Nanocrystals Fabricated by Electron Beam Evaporation
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Ministerio de Educación, Cultura y Deporte (España), Ministerio de Economía y Competitividad (España), Ibáñez Insa, Jordi [0000-0002-8909-6541], Blázquez, O., López-Conesa, L., López-Vidrier, J., Frieiro, J. L., Estradé, S., Peiró, F., Ibáñez Insa, Jordi, Hernández, S., Garrido, B., Ministerio de Educación, Cultura y Deporte (España), Ministerio de Economía y Competitividad (España), Ibáñez Insa, Jordi [0000-0002-8909-6541], Blázquez, O., López-Conesa, L., López-Vidrier, J., Frieiro, J. L., Estradé, S., Peiró, F., Ibáñez Insa, Jordi, Hernández, S., and Garrido, B.
- Abstract
Multilayers consisting of silicon nanocrystals (Si NCs) and SiO2 are successfully fabricated by electron beam evaporation, using pure Si and SiO2 targets in an oxygen-rich atmosphere for alternately depositing silicon-rich oxide (SRO) layers and SiO2 barriers, respectively. A post-deposition annealing process is carried out at different temperatures in order to achieve the Si precipitation in the form of nanocrystals. The stoichiometry of the layers is determined by X-ray photoelectron spectroscopy, which confirms the controlled silicon oxidation in order to attain SRO layers. Transmission electron microscopy and Raman-scattering measurements confirm the presence of crystalline Si-nanoprecipitates. Photoluminescence spectra from the Si NC samples can be deconvolved into two contributions, whose dynamics suggest that two different luminescent centers are responsible for the optical emission of the samples. © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
- Published
- 2019
20. Size-controlled Si nanocrystals deposited by electron beam evaporation (I.P1.33)
- Author
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Blázquez, O., López-Vidrier, J., Frieiro, J. L., López-Conesa, L., Estradé, S., Peiró, F., Ibáñez Insa, Jordi, Hernández, S., and Garrido, B.
- Abstract
Due to the quantum confinement effect, the band gap energy tunability of silicon nanocrystals (Si-NCs) is directly related to the size of these nanostructures, which has been largely studied for its implementation in photovoltaics and light-emitting devices. Chemical deposition methods have typically been employed for matrix-embedded Si-NCs fabrication, being the utilization of toxic gases a serious handicap aiming at mass production. In contrast, physical deposition methods such as electron beam evaporation (EBE) encourage the direct deposition of the material under study without chemical reactions being involved in the process. In this work, Si-NCs have been fabricated by means of EBE, by alternatively depositing SiO2 and Si layers, in an oxygen atmosphere. The stoichiometry of layers was determined by X-ray spectroscopy, which confirmed the controlled silicon oxidation in order to attain silicon-rich oxide (SRO) layers. A post-deposition annealing process was carried out at different temperatures in order to achieve the Si precipitation in the form of nanocrystals. Transmission electron microscopy confirmed the presence of crystalline Si-nanoprecipitates, which agrees with Raman scattering measurements. The photoluminescence (PL) spectra from the Si-NCs samples could be deconvolved into two contributions, whose dynamics suggests that PL is originated in two different luminescent centres. PL results will be discussed considering the possible origin of the luminescent centres and the published data in similar samples.
- Published
- 2018
21. Pathways of carrier recombination in Si/SiO2 nanocrystal superlattices
- Author
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Chlouba, T., primary, Trojánek, F., additional, Kopecký, V., additional, López-Vidrier, J., additional, Hernandéz, S., additional, Hiller, D., additional, Gutsch, S., additional, Zacharias, M., additional, and Malý, P., additional
- Published
- 2019
- Full Text
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22. Annealing temperature and barrier thickness effect on the structural and optical properties of silicon nanocrystals/SiO2 superlattices.
- Author
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López-Vidrier, J., Hernández, S., Hiller, D., Gutsch, S., López-Conesa, L., Estradé, S., Peiró, F., Zacharias, M., and Garrido, B.
- Subjects
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ELECTRO-optical effects , *SEMICONDUCTORS , *NANOCRYSTALS , *SUPERLATTICES , *ISOTHERMAL processes - Abstract
The effect of the annealing temperature and the SiO2 barrier thickness of silicon nanocrystal (NC)/ SiO2 superlattices (SLs) on their structural and optical properties is investigated. Energy-filtered transmission electron microscopy (TEM) revealed that the SL structure is maintained for annealing temperatures up to 1150 °C, with no variation on the nanostructure morphology for different SiO2 barrier thicknesses. Nevertheless, annealing temperatures as high as 1250 °C promote diffusion of Si atoms into the SiO2 barrier layers, which produces larger Si NCs and the loss of the NC size control expected from the SL approach. Complementary Raman scattering measurements corroborated these results for all the SiO2 and Si-rich oxynitride layer thicknesses. In addition, we observed an increasing crystalline fraction up to 1250 °C, which is related to a decreasing contribution of the suboxide transition layer between Si NCs and the SiO2 matrix due to the formation of larger NCs. Finally, photoluminescence measurements revealed that the emission of the superlattices exhibits a Gaussian-like lineshape with a maximum intensity after annealing at 1150 °C, indicating a high crystalline degree in good agreement with Raman results. Samples submitted to higher annealing temperatures display a progressive emission broadening, together with an increase in the central emission wavelength. Both effects are related to a progressive broadening of the size distribution with a larger mean size, in agreement with TEM observations. On the other hand, whereas the morphology of the Si NCs is unaffected by the SiO2 barrier thickness, the emission properties are slightly modified. These observed modifications in the emission lineshape allow monitoring the precipitation process of Si NCs in a direct non-destructive way. All these experimental results evidence that an annealing temperature of 1150 °C and 1-nm SiO2 barrier can be reached whilst preserving the SL structure, being thus the optimal structural SL parameters for their use in optoelectronics. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
23. Determining the crystalline degree of silicon nanoclusters/SiO2 multilayers by Raman scattering.
- Author
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Hernàndez, S., López-Vidrier, J., López-Conesa, L., Hiller, D., Gutsch, S., Ibáñez, J., Estradé, S., Peiró, F., Zacharias, M., and Garrido, B.
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RAMAN effect , *SPECTRUM analysis , *TRANSMISSION electron microscopy , *CRYSTALLIZATION , *VAPOR-plating , *CHEMICAL vapor deposition , *SILICON - Abstract
We use Raman scattering to investigate the size distribution, built-in strains and the crystalline degree of Si-nanoclusters (Si-nc) in high-quality Si-rich oxynitride/SiO2 multilayered samples obtained by plasma enhanced chemical vapor deposition and subsequent annealing at 1150 °C. An initial structural characterization of the samples was performed by means of energy-filtered transmission electron microscopy (EFTEM) and X-ray diffraction (XRD) to obtain information about the cluster size and the presence of significant amounts of crystalline phase. The contributions to the Raman spectra from crystalline and amorphous Si were analyzed by using a phonon confinement model that includes the Si-nc size distribution, the influence of the matrix compressive stress on the clusters, and the presence of amorphous Si domains. Our lineshape analysis confirms the existence of silicon precipitates in crystalline state, in good agreement with XRD results, and provides also information about the presence of a large compressive stress over the Si-nc induced by the SiO2 matrix. By using the Raman spectra from low temperature annealed samples (i.e., before the crystallization of the Si-nc), the relative scattering cross-section between crystalline and amorphous Si was evaluated as a function of the crystalline Si size. Taking into account this parameter and the integrated intensities for each phase as extracted from the Raman spectra, we were able to evaluate the degree of crystallization of the precipitated Si-nc. Our data suggest that all samples exhibit high crystalline fractions, with values up to 89% for the biggest Si-nc. The Raman study, supported by the EFTEM characterization, indicates that this system undergoes a practically abrupt phase separation, in which the precipitated Si-nanoclusters are formed by a crystalline inner part surrounded by a thin amorphous shell of approximately 1-2 atomic layers. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
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24. Absence of quantum confinement effects in the photoluminescence of Si3N4-embedded Si nanocrystals.
- Author
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Hiller, D., Zelenina, A., Gutsch, S., Dyakov, S. A., López-Conesa, L., López-Vidrier, J., Estradé, S., Peiró, F., Garrido, B., Valenta, J., Kořínek, M., Trojánek, F., Malý, P., Schnabel, M., Weiss, C., Janz, S., and Zacharias, M.
- Subjects
NANOCRYSTALS ,SPECTRUM analysis ,LUMINESCENCE ,CHEMICAL vapor deposition ,SILICON nitride - Abstract
Superlattices of Si-rich silicon nitride and Si
3 N4 are prepared by plasma-enhanced chemical vapor deposition and, subsequently, annealed at 1150 °C to form size-controlled Si nanocrystals (Si NCs) embedded in amorphous Si3 N4 . Despite well defined structural properties, photoluminescence spectroscopy (PL) reveals inconsistencies with the typically applied model of quantum confined excitons in nitride-embedded Si NCs. Time-resolved PL measurements demonstrate 105 times faster time-constants than typical for the indirect band structure of Si NCs. Furthermore, a pure Si3 N4 reference sample exhibits a similar PL peak as the Si NC samples. The origin of this luminescence is discussed in detail on the basis of radiative defects and Si3 N4 band tail states in combination with optical absorption measurements. The apparent absence of PL from the Si NCs is explained conclusively using electron spin resonance data from the Si/Si3 N4 interface defect literature. In addition, the role of Si3 N4 valence band tail states as potential hole traps is discussed. Most strikingly, the PL peak blueshift with decreasing NC size, which is often observed in literature and typically attributed to quantum confinement (QC), is identified as optical artifact by transfer matrix method simulations of the PL spectra. Finally, criteria for a critical examination of a potential QC-related origin of the PL from Si3 N4 -embedded Si NCs are suggested. [ABSTRACT FROM AUTHOR]- Published
- 2014
- Full Text
- View/download PDF
25. Structural and optical properties of size controlled Si nanocrystals in Si3N4 matrix: The nature of photoluminescence peak shift.
- Author
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Zelenina, A., Dyakov, S. A., Hiller, D., Gutsch, S., Trouillet, V., Bruns, M., Mirabella, S., Löper, P., López-Conesa, L., López-Vidrier, J., Estradé, S., Peiró, F., Garrido, B., Bläsing, J., Krost, A., Zhigunov, D. M., and Zacharias, M.
- Subjects
SUPERLATTICES ,NANOSILICON ,NANOCRYSTALS ,PHOTOLUMINESCENCE ,TRANSMISSION electron microscopy - Abstract
Superlattices of Si3N4 and Si-rich silicon nitride thin layers with varying thickness were prepared by plasma enhanced chemical vapor deposition. After high temperature annealing, Si nanocrystals were formed in the former Si-rich nitride layers. The control of the Si quantum dots size via the SiNx layer thickness was confirmed by transmission electron microscopy. The size of the nanocrystals was well in agreement with the former thickness of the respective Si-rich silicon nitride layers. In addition X-ray diffraction evidenced that the Si quantum dots are crystalline whereas the Si3N4 matrix remains amorphous even after annealing at 1200 °C. Despite the proven Si nanocrystals formation with controlled sizes, the photoluminescence was 2 orders of magnitude weaker than for Si nanocrystals in SiO2 matrix. Also, a systematic peak shift was not found. The SiNx/Si3N4 superlattices showed photoluminescence peak positions in the range of 540-660 nm (2.3-1.9 eV), thus quite similar to the bulk Si3N4 film having peak position at 577 nm (2.15 eV). These rather weak shifts and scattering around the position observed for stoichiometric Si3N4 are not in agreement with quantum confinement theory. Therefore theoretical calculations coupled with the experimental results of different barrier thicknesses were performed. As a result the commonly observed photoluminescence red shift, which was previously often attributed to quantum-confinement effect for silicon nanocrystals, was well described by the interference effect of Si3N4 surrounding matrix luminescence. [ABSTRACT FROM AUTHOR]
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- 2013
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26. Resistive switching and charge transport mechanisms in ITO/ZnO/p-Si devices
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Universitat Politècnica de València. Departamento de Comunicaciones - Departament de Comunicacions, Agencia Estatal de Investigación, Ministerio de Economía y Empresa, Ministerio de Economía y Competitividad, Blázquez, O., Frieiro, J.L., López-Vidrier, J., Guillaume, C., Portier, X., Labbé, C., Sanchis Kilders, Pablo, Hernández, S., Garrido, B., Universitat Politècnica de València. Departamento de Comunicaciones - Departament de Comunicacions, Agencia Estatal de Investigación, Ministerio de Economía y Empresa, Ministerio de Economía y Competitividad, Blázquez, O., Frieiro, J.L., López-Vidrier, J., Guillaume, C., Portier, X., Labbé, C., Sanchis Kilders, Pablo, Hernández, S., and Garrido, B.
- Abstract
[EN] The resistive switching properties of ITO/ZnO/p-Si devices have been studied, which present well-defined resistance states with more than five orders of magnitude difference in current. Both the high resistance state (HRS) and the low resistance state (LRS) were induced by either sweeping or pulsing the voltage, observing some differences in the HRS. Finally, the charge transport mechanisms dominating the pristine, HRS, and LRS states have been analyzed in depth, and the obtained structural parameters suggest a partial re-oxidation of the conductive nanofilaments and a reduction of the effective conductive area.
- Published
- 2018
27. Green Electroluminescence of Al/Tb/Al/SiO2 Devices Fabricated by Electron Beam Evaporation
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Ministerio de Economía y Competitividad (España), Frieiro, J. L., Blázquez, O., López-Vidrier, J., López-Conesa, L., Estradé, S., Peiró, F., Ibáñez Insa, Jordi, Hernàndez, Sergi, Garrido, B., Ministerio de Economía y Competitividad (España), Frieiro, J. L., Blázquez, O., López-Vidrier, J., López-Conesa, L., Estradé, S., Peiró, F., Ibáñez Insa, Jordi, Hernàndez, Sergi, and Garrido, B.
- Abstract
In this work, the fabrication and the structural, optical and electrical properties of Al-Tb/SiO2 nanomultilayers have been studied. The nanomultilayers were deposited by means of electron beam evaporation on top of p-type Si substrates. Optical characterization shows a narrow and strong emission in the green spectral range, indicating the optical activation of Tb3+ ions. The electrical characterization revealed conduction limited by the electrode, although trapped-assisted mechanisms can also contribute to transport. The electroluminescence analysis revealed also emission from Tb3+ ions, a promising result to include this material in future optoelectronics applications as integrated light-emitting devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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- 2018
28. Resistive switching and charge transport mechanisms in ITO/ZnO/p-Si devices
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Blázquez, O., primary, Frieiro, J. L., additional, López-Vidrier, J., additional, Guillaume, C., additional, Portier, X., additional, Labbé, C., additional, Sanchis, P., additional, Hernández, S., additional, and Garrido, B., additional
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- 2018
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29. Memristive behaviour of Si-Al oxynitride thin films: the role of oxygen and nitrogen vacancies in the electroforming process
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Blázquez, O, primary, Martín, G, additional, Camps, I, additional, Mariscal, A, additional, López-Vidrier, J, additional, Ramírez, J M, additional, Hernández, S, additional, Estradé, S, additional, Peiró, F, additional, Serna, R, additional, and Garrido, B, additional
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- 2018
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30. Boron-incorporating silicon nanocrystals embedded in SiO2: Absence of free carriers vs. B-induced defects
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Hiller, D, López-Vidrier, J, Gutsch, S, Zacharias, M, Wahl, M, Bock, W, Brodyanski, A, Kopnarski, M, Nomoto, K, Valenta, J, König, D, Hiller, D, López-Vidrier, J, Gutsch, S, Zacharias, M, Wahl, M, Bock, W, Brodyanski, A, Kopnarski, M, Nomoto, K, Valenta, J, and König, D
- Abstract
© 2017 The Author(s). Boron (B) doping of silicon nanocrystals requires the incorporation of a B-atom on a lattice site of the quantum dot and its ionization at room temperature. In case of successful B-doping the majority carriers (holes) should quench the photoluminescence of Si nanocrystals via non-radiative Auger recombination. In addition, the holes should allow for a non-transient electrical current. However, on the bottom end of the nanoscale, both substitutional incorporation and ionization are subject to significant increase in their respective energies due to confinement and size effects. Nevertheless, successful B-doping of Si nanocrystals was reported for certain structural conditions. Here, we investigate B-doping for small, well-dispersed Si nanocrystals with low and moderate B-concentrations. While small amounts of B-atoms are incorporated into these nanocrystals, they hardly affect their optical or electrical properties. If the B-concentration exceeds ~1 at%, the luminescence quantum yield is significantly quenched, whereas electrical measurements do not reveal free carriers. This observation suggests a photoluminescence quenching mechanism based on B-induced defect states. By means of density functional theory calculations, we prove that B creates multiple states in the bandgap of Si and SiO2. We conclude that non-percolated ultra-small Si nanocrystals cannot be efficiently B-doped.
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- 2017
31. Defect-Induced Luminescence Quenching vs. Charge Carrier Generation of Phosphorus Incorporated in Silicon Nanocrystals as Function of Size
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Hiller, D, López-Vidrier, J, Gutsch, S, Zacharias, M, Nomoto, K, König, D, Hiller, D, López-Vidrier, J, Gutsch, S, Zacharias, M, Nomoto, K, and König, D
- Abstract
© The Author(s) 2017. Phosphorus doping of silicon nanostructures is a non-trivial task due to problems with confinement, self-purification and statistics of small numbers. Although P-atoms incorporated in Si nanostructures influence their optical and electrical properties, the existence of free majority carriers, as required to control electronic properties, is controversial. Here, we correlate structural, optical and electrical results of size-controlled, P-incorporating Si nanocrystals with simulation data to address the role of interstitial and substitutional P-atoms. Whereas atom probe tomography proves that P-incorporation scales with nanocrystal size, luminescence spectra indicate that even nanocrystals with several P-atoms still emit light. Current-voltage measurements demonstrate that majority carriers must be generated by field emission to overcome the P-ionization energies of 110-260 meV. In absence of electrical fields at room temperature, no significant free carrier densities are present, which disproves the concept of luminescence quenching via Auger recombination. Instead, we propose non-radiative recombination via interstitial-P induced states as quenching mechanism. Since only substitutional-P provides occupied states near the Si conduction band, we use the electrically measured carrier density to derive formation energies of ∼400 meV for P-atoms on Si nanocrystal lattice sites. Based on these results we conclude that ultrasmall Si nanovolumes cannot be efficiently P-doped.
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- 2017
32. Si-Al oxynitride thin films for memristive switching applications
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Blázquez, O., Ramírez, J. M., Camps, I., López-Vidrier, J., Hernández, S., Serna, Rosalía, and Garrido, B.
- Abstract
Lille (France) from May 2 to 6, 2016 ; http://www.european-mrs.com/meetings/2016-spring-meeting, Resume : Recently, memristive materials have attracted high interest in the quest for improved electronic and optoelectronic functionalities in silicon technology. Memristive materials memorize the resistance (either in a high or in a low resistance state) after switching off the voltage. Thus, it can be used as an electronic memory (ReRAM) or as an optically readable memory if some optical property (e.g. absorption or light emission) varies between the two states. On the other hand, Si-Al oxynitride (SiAlON) is a material highly compatible with silicon technology that is devised to improve the properties of silicon oxynitrides by adding some Al percentage (1-10%). This allows to reduce the band-gap below silicon nitride (5.5 eV), to improve the conductivity depending on Al concentration, and to help to create memristance through the proper interaction with an Al electrode. In this work, we present an electrical characterization of 100-nm thick SiAlON thin films fabricated by means of pulsed laser deposition on p-type Si substrates. A vertical device structure was achieved by using a shadow mask and depositing either aluminium or indium tin oxide (ITO) on top of the films and full-area Al on the rear side of the substrate. Intensity versus voltage curves have shown a clear switching between two different resistivity states from 10^6 to 10^2 Ohm, showing a good switching repeatability for the two types of contacts. However, the voltage threshold for switching depends on the contact material, being lower in the case of the ITO contact, probably due to its higher ability to interchange oxygen atoms. Finally, the films were also doped with Eu to explore their optoelectronic properties, keeping their memristive switching behaviour.
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- 2016
33. Modulation of the electroluminescence emission from ZnO/Si NCs/p-Si light-emitting devices via pulsed excitation
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López-Vidrier, J., primary, Gutsch, S., additional, Blázquez, O., additional, Hiller, D., additional, Laube, J., additional, Kaur, R., additional, Hernández, S., additional, Garrido, B., additional, and Zacharias, M., additional
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- 2017
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34. Structural, Vibrational, and Electronic Study of Sb2S3 at High Pressure
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Universitat Politècnica de València. Instituto de Diseño para la Fabricación y Producción Automatizada - Institut de Disseny per a la Fabricació i Producció Automatitzada, Universitat Politècnica de València. Escuela Técnica Superior de Ingeniería del Diseño - Escola Tècnica Superior d'Enginyeria del Disseny, Universitat Politècnica de València. Escuela Politécnica Superior de Alcoy - Escola Politècnica Superior d'Alcoi, Ministerio de Economía y Competitividad, Universitat Politècnica de València, Ibáñez, Jordi, Sans-Tresserras, Juan Ángel, Popescu, Catalin, López-Vidrier, J., Elvira-Betanzos, J.J., Cuenca Gotor, Vanesa Paula, Gomis, O., Manjón Herrera, Francisco Javier, Rodríguez-Hernández, P., Muñoz, Alfonso, Universitat Politècnica de València. Instituto de Diseño para la Fabricación y Producción Automatizada - Institut de Disseny per a la Fabricació i Producció Automatitzada, Universitat Politècnica de València. Escuela Técnica Superior de Ingeniería del Diseño - Escola Tècnica Superior d'Enginyeria del Disseny, Universitat Politècnica de València. Escuela Politécnica Superior de Alcoy - Escola Politècnica Superior d'Alcoi, Ministerio de Economía y Competitividad, Universitat Politècnica de València, Ibáñez, Jordi, Sans-Tresserras, Juan Ángel, Popescu, Catalin, López-Vidrier, J., Elvira-Betanzos, J.J., Cuenca Gotor, Vanesa Paula, Gomis, O., Manjón Herrera, Francisco Javier, Rodríguez-Hernández, P., and Muñoz, Alfonso
- Abstract
Antimony trisulfide (Sb2S3), found in nature as the mineral stibnite, has been studied under compression at room temperature from a joint experimental and theoretical perspective. X-ray diffraction and Raman scattering measurements are complemented with ab initio total-energy, lattice-dynamics, and electronic structure calculations. The continuous changes observed in the volume, lattice parameters, axial ratios, bond lengths, and Raman mode frequencies as a function of pressure can be attributed to the different compressibility along the three orthorhombic axes in different pressure ranges, which in turn are related to the different compressibility of several interatomic bond distances in different pressure ranges. The structural and vibrational properties of Sb2S3 under compression are compared and discussed in relation to isostructural Bi2S3 and Sb2Se3. No first-order phase transition has been observed in Sb2S3 up to 25 GPa, in agreement with the stability of the Pnma structure in Bi2S3 and Sb2Se3 previously reported up to 50 GPa. Our measurements and calculations do not show evidence either for a pressure-induced second-order isostructural phase transition or for an electronic topological transition in Sb2S3.
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- 2016
35. Structural, Vibrational, and Electronic Study of Sb2S3 at High Pressure
- Author
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Ministerio de Educación, Cultura y Deporte (España), Ministerio de Economía y Competitividad (España), Ibáñez Insa, Jordi, Sans, Juan Ángel, Popescu, Catalin, López-Vidrier, J., Elvira, Josep, Cuenca-Gotor, V. P., Gomis, Óscar, Manjón, F. J., Rodríguez-Hernández, Pablo Rogelio, Muñoz, Alfonso, Ministerio de Educación, Cultura y Deporte (España), Ministerio de Economía y Competitividad (España), Ibáñez Insa, Jordi, Sans, Juan Ángel, Popescu, Catalin, López-Vidrier, J., Elvira, Josep, Cuenca-Gotor, V. P., Gomis, Óscar, Manjón, F. J., Rodríguez-Hernández, Pablo Rogelio, and Muñoz, Alfonso
- Abstract
Antimony trisulfide (Sb2S3), found in nature as the mineral stibnite, has been studied under compression at room temperature from a joint experimental and theoretical perspective. X-ray diffraction and Raman scattering measurements are complemented with ab initio total-energy, lattice-dynamics, and electronic structure calculations. The continuous changes observed in the volume, lattice parameters, axial ratios, bond lengths, and Raman mode frequencies as a function of pressure can be attributed to the different compressibility along the three orthorhombic axes in different pressure ranges, which in turn are related to the different compressibility of several interatomic bond distances in different pressure ranges. The structural and vibrational properties of Sb2S3 under compression are compared and discussed in relation to isostructural Bi2S3 and Sb2Se3. No first-order phase transition has been observed in Sb2S3 up to 25 GPa, in agreement with the stability of the Pnma structure in Bi2S3 and Sb2Se3 previously reported up to 50 GPa. Our measurements and calculations do not show evidence either for a pressure-induced second-order isostructural phase transition or for an electronic topological transition in Sb2S3. © 2016 American Chemical Society.
- Published
- 2016
36. Structural, optical and electrical properties of silicon nanocrystals embedded in SixC1−x/SiC multilayer systems for photovoltaic applications
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López-Vidrier, J., Hernández, S., Samà, J., Canino, M., Allegrezza, M., Bellettato, M., Shukla, R., Schnabel, M., Löper, P., López-Conesa, L., Estradé, S., Peiró, F., Janz, S., and Garrido, B.
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- 2013
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37. Structural and optical properties of Al-Tb/SiO2 multilayers fabricated by electron beam evaporation
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Blázquez, O., primary, López-Vidrier, J., additional, López-Conesa, L., additional, Busquets-Masó, M., additional, Estradé, S., additional, Peiró, F., additional, Hernández, S., additional, and Garrido, B., additional
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- 2016
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38. Structural, Vibrational, and Electronic Study of Sb2S3 at High Pressure
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Ibáñez, J., primary, Sans, J. A., additional, Popescu, C., additional, López-Vidrier, J., additional, Elvira-Betanzos, J. J., additional, Cuenca-Gotor, V. P., additional, Gomis, O., additional, Manjón, F. J., additional, Rodríguez-Hernández, P., additional, and Muñoz, A., additional
- Published
- 2016
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39. Silicon nanocrystals embedded in silicon carbide as a wide-band gap photovoltaic material
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López-Vidrier, J., primary, Löper, P., additional, Schnabel, M., additional, Hernández, S., additional, Canino, M., additional, Summonte, C., additional, Janz, S., additional, and Garrido, B., additional
- Published
- 2016
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40. Flexible inkjet printed high-k HfO2-based MIM capacitors
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Vescio, G., primary, López-Vidrier, J., additional, Leghrib, R., additional, Cornet, A., additional, and Cirera, A., additional
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- 2016
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41. Optical emission from Si O2 -embedded silicon nanocrystals: A high-pressure Raman and photoluminescence study
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Ibáñez Insa, Jordi, Hernández, S., López-Vidrier, J., Hiller, D., Gutsch, S., Zacharias, M., Segura, A., Valenta, J., Garrido, B., Ibáñez Insa, Jordi, Hernández, S., López-Vidrier, J., Hiller, D., Gutsch, S., Zacharias, M., Segura, A., Valenta, J., and Garrido, B.
- Abstract
© 2015 American Physical Society. We investigate the optical properties of high-quality Si nanocrystals (NCs)/SiO2 multilayers under high hydrostatic pressure with Raman scattering and photoluminescence (PL) measurements. The aim of our study is to shed light on the origin of the optical emission of the Si NCs/SiO2. The Si NCs were produced by chemical-vapor deposition of Si-rich oxynitride (SRON)/SiO2 multilayers with 5- and 4-nm SRON layer thicknesses on fused silica substrates and subsequent annealing at 1150°C, which resulted in the precipitation of Si NCs with an average size of 4.1 and 3.3 nm, respectively. From the pressure dependence of the Raman spectra we extract a phonon pressure coefficient of 8.5±0.3cm-1/GPa in both samples, notably higher than that of bulk Si(5.1cm-1/GPa). This result is ascribed to a strong pressure amplification effect due to the larger compressibility of the SiO2 matrix. In turn, the PL spectra exhibit two markedly different contributions: a higher-energy band that redshifts with pressure, and a lower-energy band which barely depends on pressure and which can be attributed to defect-related emission. The pressure coefficients of the higher-energy contribution are (-27±6) and (-35±8)meV/GPa for the Si NCs with a size of 4.1 and 3.3 nm, respectively. These values are sizably higher than those of bulk Si(-14meV/GPa). When the pressure amplification effect observed by Raman scattering is incorporated into the analysis of the PL spectra, it can be concluded that the pressure behavior of the high-energy PL band is consistent with that of the indirect transition of Si and, therefore, with the quantum-confined model for the emission of the Si NCs.
- Published
- 2015
42. Structural and optical properties of size controlled Si nanocrystals in Si3N4 matrix
- Author
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Zelenina, A., Dyakov, S.A., Hiller, D., Gutsch, S., Trouillet, V., Bruns, M., Mirabella, S., Löper, P., López-Conesa, L., López-Vidrier, J., Estrade, S., Peiro, F., Garrido, B., Bläsing, J., Krost, A., Zhigunov, D.M., Zacharias, M., and Publica
- Subjects
Silicium-Photovoltaik ,Neuartige Konzepte ,Farbstoff ,nanocrystals ,Herstellung und Analyse von hocheffizienten Solarzellen ,Nitride ,Organische und Neuartige Solarzellen ,Alternative Photovoltaik-Technologien ,Photoluminescence ,Tandemsolarzellen auf kristallinem Silicium ,Solarzellen - Entwicklung und Charakterisierung - Abstract
Superlattices of Si3N4 and Si-rich silicon nitride thin layers with varying thickness were prepared by plasma enhanced chemical vapor deposition. After high temperature annealing, Si nanocrystals were formed in the former Si-rich nitride layers. The control of the Si quantum dots size via the SiNx layer thickness was confirmed by transmission electron microscopy. The size of the nanocrystals was well in agreement with the former thickness of the respective Si-rich silicon nitride layers. In addition X-ray diffraction evidenced that the Si quantum dots are crystalline whereas the Si3N4 matrix remains amorphous even after annealing at 1200 degrees C. Despite the proven Si nanocrystals formation with controlled sizes, the photoluminescence was 2 orders of magnitude weaker than for Si nanocrystals in SiO2 matrix. Also, a systematic peak shift was not found. The SiNx/Si3N4 superlattices showed photoluminescence peak positions in the range of 540-660nm (2.3-1.9 eV), thus quite similar to the bulk Si3N4 film having peak position at 577nm (2.15 eV). These rather weak shifts and scattering around the position observed for stoichiometric Si3N4 are not in agreement with quantum confinement theory. Therefore theoretical calculations coupled with the experimental results of different barrier thicknesses were performed. As a result the commonly observed photoluminescence red shift, which was previously often attributed to quantum-confinement effect for silicon nanocrystals, was well described by the interference effect of Si3N4 surrounding matrix luminescence.
- Published
- 2013
43. Processing and characterization of tandem solar cells from crystalline silicon materials
- Author
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Janz, S., Schnabel, M., Löper, P., Summonte, C., Canino, M., López-Vidrier, J., Hernández, S., Garrido, B., and Glunz, S.W.
- Subjects
Quantum Dots ,Device4s ,MATERIAL STUDIES, NEW CONCEPTS, ULTRA-HIGH EFFICIENCY AND SPACE TECHNOLOGY ,Nanoparticles ,Tandem ,New Materials and Concepts for Cells - Abstract
28th European Photovoltaic Solar Energy Conference and Exhibition; 142-146, We present the first crystalline Si-based tandem solar cell device consisting of a monolithically interconnected c-Si wafer bottom and a Si nanocrystal (NC) top solar cell. The major part of this work has been realised within a European consortium in the frame of the FP7 project NASCEnT. Within this project we have been able to (i) develop new nanomaterials with photovoltaic compatible technologies, to (ii) improve the theoretical understanding of transport, recombination and dopant incorporation in these quantum confined absorber materials and to (iii) design devices which enable us to prove quantum confinement. In this publication we show that although solid phase crystallisation at 1100 °C for around 30 min is necessary to generate Si NCs of proper quality the wafer bottom cell as well as the c-SiC(n+) tunnel recombination junction layer can withstand such harsh conditions. Besides simulations to determine the influence of the high thermal budget on dopant profiles in wafer and c-SiC lifetime measurements on parallel processed wafers still show minority carrier lifetimes of 600 μs. The bifacial character of the tandem device enables us to clearly distinguish between bottom and top cell contributions. With a NC layer thickness of initially 3 nm Voc values as high as 978 mV could be achieved at 1 sun illumination from the front-side. Under rear-side illumination the short circuit current Jsc is with 1.0 mA/cm2 4 times higher that under front side illumination due to the better absorption and carrier lifetime of the bottom cell but still limited by the series resistance of the intrinsic NC absorber material. However, at 510 mV the Voc is much lower, indicating the difference in Voc is due to photogenerated voltage in the NC top cell which can only be created by illumination with low-wavelength light, i.e. front illumination. This very first tandem solar cell device including quantum dot absorber layers produced with photovoltaic compatible processes is the next step to successfully overcome the Shockley-Queisser limit for wafer based Si solar cells.
- Published
- 2013
44. Silicon quantum dots in photovoltaic devices: device fabrication, characterization and comparison of materials
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Löper, P., Canino, M., López-Vidrier, J., Schnabel, M., Witzky, A., Bellettato, M., Allegrezza, M., Hiller, D., Hartel, A., Gutsch, S., Hernández, S., Guerra, R., Ossicini, S., Garrido, B., Janz, S., and Zacharias, M.
- Subjects
Photovoltaics ,Silicon Nanostructures ,Material Studies, New Concepts and Ultra-High Efficiency ,New Materials, Cells and Modules ,Silicon Nanostructures, Photovoltaics - Abstract
27th European Photovoltaic Solar Energy Conference and Exhibition; 35-40, Silicon nanocrystals (Si NCs) embedded in Si-based dielectrics provide a Si-based high band gap material (1.7 eV) and enable the construction of all-crystalline Si tandem solar cells. However, Si nanocrystal formation involves high-temperature annealing which deteriorates the properties of any previously established selective contacts. The inter-diffusion of dopants during high-temperature annealing alters Si NC formation and limits the built-in voltage. Furthermore, most devices presented so far also involve electrically active bulk Si and therefore do not allow a clear separation of the observed photovoltaic effect of the quantum dot layer from that of the bulk Si substrate. A membrane route is presented for quantum dot based p-i-n solar cells to overcome these limitations. In this approach, the formation of both selective contacts is carried out after high-temperature annealing and therefore not affected by the latter. P-i-n solar cells are investigated with Si NCs embedded in silicon carbide in the intrinsic region. Open-circuit voltages of up to 370 mV are shown for the NC layer. An optical model of the device is presented for improving the cell current. Finally device failure due to damaged insulation layers is analysed by electron beam induced current measurements.
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- 2012
45. The NASCENT Project
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Janz, S., Löper, P., Schnabel, M., Zacharias, M., Hiller, D., Gutsch, S., Hartel, A.M., Summonte, C., Canino, M., Allegrezza, M., Ossicini, S., Guerra, R., Marri, I., Garrido, B., Hernández, S., López-Vidrier, J., Valenta, J., Kubera, T., Foti, M., and Gerardi, C.
- Subjects
Advanced Photovoltaics : New Concepts and Ultra-High Efficiency ,New Materials, Cells and Modules - Abstract
26th European Photovoltaic Solar Energy Conference and Exhibition; 22-27, We present an overview of the project NASCEnT and the first results we were able to achieve after one year of project duration. The overall objective of the project is to develop new nano-materials with new production technologies and to fabricate silicon quantum dot (Si QD) materials for all-silicon tandem solar cells to achieve increased efficiencies. The understanding of electrical transport and recombination mechanisms in these newly developed nano-materials will enable us to design novel solar cell structures that help to overcome the efficiency limits of conventional solar cell concepts. So far we developed simple device structures and process sequences for both material systems (Si QDs in silicon oxide and silicon carbide) and tested a pin solar cell structure. Another objective of the project is to ensure the compatibility of the newly developed technologies with high-throughput processing leading to further cost-reduction. Within the scope of this project the novel concept of band gap-tuneable quantum dot superlattices is to be exploited in combination with a wafer-based high efficiency silicon solar cell as well as with a thin-film solar cell structure. The outcome of the project will be significant progress in solar cell evolution and will lead to higher efficiencies for solar cells and to ongoing cost-reductions from both a short-term and a long-term perspective.
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- 2011
- Full Text
- View/download PDF
46. Optical emission fromSiO2-embedded silicon nanocrystals: A high-pressure Raman and photoluminescence study
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Ibáñez, J., primary, Hernández, S., additional, López-Vidrier, J., additional, Hiller, D., additional, Gutsch, S., additional, Zacharias, M., additional, Segura, A., additional, Valenta, J., additional, and Garrido, B., additional
- Published
- 2015
- Full Text
- View/download PDF
47. Luminescence yield in Al and Tb3+delta-doped oxide thin films fabricated by electron beam evaporation
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Blázquez, O., additional, Ramírez, J. M., additional, López-Vidrier, J., additional, Berencén, Y., additional, Hernández, S., additional, Sanchis, P., additional, and Garrido, B., additional
- Published
- 2015
- Full Text
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48. Charge transport in nanocrystalline SiC with and without embedded Si nanocrystals
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Schnabel, M., primary, Canino, M., additional, Kühnhold-Pospischil, S., additional, López-Vidrier, J., additional, Klugermann, T., additional, Weiss, C., additional, López-Conesa, L., additional, Zschintzsch-Dias, M., additional, Summonte, C., additional, Löper, P., additional, Janz, S., additional, and Wilshaw, P. R., additional
- Published
- 2015
- Full Text
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49. Observation of Room Temperature Photoluminescence from Asymmetric CuGaO2/ZnO/ZnMgO Multiple Quantum Well Structures
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Aneesh, P. M., primary, Jayaraj, M. K., additional, Reshmi, R., additional, Ajimsha, R. S., additional, Kukreja, L. M., additional, Aldrin, A., additional, Rojas, F., additional, Bertomeu, J., additional, LóPez-Vidrier, J., additional, and HernáNdez, S., additional
- Published
- 2015
- Full Text
- View/download PDF
50. Structural parameters effect on the electrical and electroluminescence properties of silicon nanocrystals/SiO2 superlattices
- Author
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López-Vidrier, J, primary, Berencén, Y, additional, Hernández, S, additional, Mundet, B, additional, Gutsch, S, additional, Laube, J, additional, Hiller, D, additional, Löper, P, additional, Schnabel, M, additional, Janz, S, additional, Zacharias, M, additional, and Garrido, B, additional
- Published
- 2015
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