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139 results on '"Nadaud, Kevin"'

1. Enhancement of piezoelectric properties in a narrow cerium doping range of $\text{Ba}_{1-x}\text{Ca}_{x}\text{Ti}_{1-y}\text{Zr}_{y}\text{O}_{3}$ evidenced by high throughput experiment

Author

Nadaud, Kevin, Nataf, Guillaume F., Jaber, Nazir, Negulescu, Béatrice, Giovannelli, Fabien, Andreazza, Pascal, Birnal, Pierre, and Wolfman, Jérôme

Subjects
Condensed Matter - Materials Science
Abstract

Lead-free materials based on the $\text{(Ba,Ca)(Zr,Ti)O}_{3}$ (BCZT) system exhibit excellent electromechanical properties that can be strongly modified by small amounts of dopants. Here, we use a high throughput strategy to unravel the influence of aliovalent doping with Ce on dielectric and piezoelectric properties of BCTZ. We synthesize and characterize a single BCTZ thin film with a composition gradient from undoped to 0.2 mol % cerium doping. The cerium doping increases the piezoelectric coefficient from $42.3\pm 2.9 \text{pm V}^{-1}$ (undoped) to $63\pm 2.4 \text{pm V}^{-1}$ for 0.06 Ce-mol\%, and then decreases to $38.4 \pm 1.3 \text{pm V}^{-1}$ for the maximum amount of cerium (0.2 mol %). An investigation of sub-coercive field non-linearities reveal that these variations are not only induced by changes in dynamics and densities of domain walls. The results highlight the advantage of high throughput techniques to identify ideal compositions for applications, without synthesizing a high number of samples with unavoidable sample-to-sample variations.

Published
2024
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2. Effect of thermal annealing on dielectric and ferroelectric properties of aerosol-deposited $0.65\text{Pb}(\text{Mg}_{1/3}\text{Nb}_{2/3})\text{O}_{3}-0.35\text{PbTiO}_{3}$ thick films

Author

Nadaud, Kevin, Sadl, Matej, Bah, Micka, Levassort, Franck, and Ursic, Hana

Subjects
Condensed Matter - Materials Science
Abstract

In this work, the effects of thermal annealing at 500 {\deg}C on aerosol-deposited $0.65\text{Pb}(\text{Mg}_{1/3}\text{Nb}_{2/3})\text{O}_{3}-0.35\text{PbTiO}_{3}$ thick films on stainless-steel substrates are investigated using two complementary methods at high and low applied external electric fields. The first one is Positive Up Negative Down method, which allows us to obtain information about the switching and non-switching contributions to the polarization. It shows that the as-deposited film is ferroelectric before annealing, since it has a switching contribution to the polarization. After annealing, both the switching and non-switching contributions to polarization increased by a factor of 1.6 and 2.33, respectively, indicating stronger ferroelectric behavior. The second method is based on impedance spectroscopy coupled with Rayleigh analysis. The results show that post-deposition thermal annealing increases the reversible domain wall contribution to the dielectric permittivity by a factor 11 while keeping the threshold field similar. This indicates, after annealing, domain wall density is larger while domain wall mobility remains similar. These two complementary characterization methods show that annealing increases the ferroelectric behavior of the thick film by increasing the domain wall density and its influence is visible both on polarization versus electric field loop and dielectric permittivity.

Published
2023
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3. Subcoercive-field dielectric response of $0.5(\text{Ba}_{0.7}\text{Ca}_{0.3}\text{TiO}_{3})-0.5(\text{BaZr}_{0.2}\text{Ti}_{0.8}\text{O}_{3})$ thin film: peculiar third harmonic signature of phase transitions and residual ferroelectricity

Author

Nadaud, Kevin, Nataf, Guillaume F., Jaber, Nazir, Bah, Micka, Negulescu, Béatrice, Andreazza, Pascal, Birnal, Pierre, and Wolfman, Jérôme

Subjects
Condensed Matter - Materials Science
Abstract

Sub-coercive field non-linearities in $0.5(\text{Ba}_{0.7}\text{Ca}_{0.3}\text{TiO}_{3})-0.5(\text{BaZr}_{0.2}\text{Ti}_{0.8}\text{O}_{3})$ (BCTZ 50/50) thin film elaborated using pulsed laser deposition are studied using permittivity and phase angle of the third harmonic measurements as function of the AC measuring field $E_{\mathit{AC}}$ and temperature. The global phase transition temperature $T_{\mathit{max}}$ for which the permittivity is maximum, decreases from 330 K to 260 K when $E_{\mathit{AC}}$ increases. Rayleigh analysis of the AC field dependence of the relative permittivity shows a regular decrease of the domain wall motion contributions as temperature increases up to $T_{\mathit{max}}$ and an even more pronounced decrease above $T_{\mathit{max}}$. This measurement reveals that the ferroelectric behavior subsists 70 K above the global phase transition. The phase angle of the third harmonic at temperatures below 275 K, is characteristic of a conventional ferroelectric and from 275 K to $T_{\mathit{max}}=$ 330 K of a relaxor. Above $T_{\mathit{max}}$, the thin film exhibits a peculiar phase angle of the third harmonic, which consists of ${-180}{\deg}\rightarrow {-225}{\deg}\rightarrow {+45}{\deg} \rightarrow {0}{\deg}$ instead of the ${-180}{\deg}\rightarrow {-90}{\deg} \rightarrow {0}{\deg}$ found for relaxor. This peculiar behavior is observed only on heating, and is tentatively attributed to changes in the correlations between polar nanoregions.

Published
2023
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6. Strategies to Enhance ZnO Nanogenerator Performance via Thermal-Annealing and Cryo-Cooling

Author

Poulin-Vittrant, Guylaine, Nadaud, Kevin, Chandraiahgari, Chandrakanth Reddy, and Alquier, Daniel

Subjects
Condensed Matter - Materials Science
Abstract

Piezoelectric capacitive NanoGenerators (NG) based on vertically grown crystalline zinc oxide nanowires (ZnO-NWs) have been fabricated using a low-cost and scalable hydrothermal method on gold-coated silicon substrates, which served as both a seed layer and a conductive bottom electrode. Morphological and structural characterizations demonstrate that the obtained ZnO NWs are dense, uniformly distributed, vertically well aligned and exhibit good crystal quality. The piezoelectric NG consists of ZnO-NWs grown on a gold-coated silicon substrate, parylene-C matrix, titanium/aluminium top electrode and poly(dimethylsiloxane) (PDMS) encapsulating layer. In order to enhance the NG performances, which is the main goal of this study, two distinctly different post-growth treatments, namely thermal annealing in ambient air and cryo-cooling by immersion in liquid nitrogen, are applied and their effect studied. Achieving the high performance of NG via the combination of high-quality NWs growth and subsequent post-growth treatment is presented. Superior global performance of NG has been observed with a post-treatment of cryo-cooling for an optimum duration compared to the thermal annealing signifies the simplicity and novelty of the work. The proposed strategies highlight the role of post-growth treatments towards the fabrication of high-performance functional NG to be incorporated into future smart objects.

Published
2020

10. Metastable and field-induced ferroelectric response in antiferroelectric lead zirconate thin film studied by the hyperbolic law and third harmonic response.

Author

Nadaud, Kevin, Borderon, Caroline, Renoud, Raphaël, Bah, Micka, Ginestar, Stephane, and Gundel, Hartmut W.

Subjects
*THIN films, *LEGAL education, *FERROELECTRIC transitions, *FERROELECTRIC materials, *FERROELECTRICITY
Abstract

In this paper, the field-induced residual ferroelectricity in antiferroelectric lead zirconate thin films has been studied by impedance measurements together with a hyperbolic law analysis, which permits us to extract the different contributions to the material's complex permittivity. By measuring the Rayleigh coefficient α r , it appears that the residual ferroelectricity is considerably enhanced when the sample has been previously exposed to an electric field close to the antiferroelectric to ferroelectric transition field. This indicates that a part of the material remains ferroelectric after the antiferroelectric–ferroelectric backward transition, which constitutes an additional contribution to polarization. Consequently, a higher domain wall density and mobility can be observed. Measurements after exposition to thermal treatment show that this ferroelectric response is metastable. [ABSTRACT FROM AUTHOR]

Published
2023
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16. Subcoercive field dielectric response of 0.5(Ba0.7Ca0.3TiO3)-0.5(BaZr0.2Ti0.8O3) thin film: Peculiar third harmonic signature of phase transitions and residual ferroelectricity.

Author

Nadaud, Kevin, Nataf, Guillaume F., Jaber, Nazir, Bah, Micka, Negulescu, Béatrice, Andreazza, Pascal, Birnal, Pierre, and Wolfman, Jérôme

Subjects
PHASE transitions, THIN films, FERROELECTRICITY, PULSED laser deposition, TRANSITION temperature, BARIUM titanate
Abstract

Subcoercive field non-linearities in 0.5(Ba0.7Ca0.3TiO3)-0.5(BaZr0.2Ti0.8O3) (BCTZ 50/50) thin film elaborated using pulsed laser deposition are studied using permittivity and phase angle of the third harmonic measurements as a function of the AC measuring field E A C and temperature. The global phase transition temperature T max for which the permittivity is maximum, decreases from 330 to 260 K when E A C increases. Rayleigh analysis of the AC field dependence of the relative permittivity shows a regular decrease in the domain wall motion contributions as temperature increases up to T max and an even more pronounced decrease above T max . This measurement reveals that the ferroelectric behavior subsists 70 K above the global phase transition. The phase angle of the third harmonic at temperatures below 275 K is characteristic of a conventional ferroelectric and from 275 K to T max = 330 K of a relaxor. Above T max , the thin film exhibits a peculiar phase angle of the third harmonic, which consists of − 180 ° → − 225 ° → + 45 ° → 0 ° instead of the − 180 ° → − 90 ° → 0 ° found for relaxor. This peculiar behavior is observed only on heating and is tentatively attributed to changes in the correlations between polar nanoregions. [ABSTRACT FROM AUTHOR]

Published
2024
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22. Influence of deciding/synthesis parameters of hydrothermally grown ZnO nanowires for FTO - free perovskite solar cells

Author

Sekar, Karthick, Nakar, Rana, Doineau, Raphaël, Bouclé, Johann, Schmaltz, Bruno, Nadaud, Kevin, Poulin-Vittrant, Guylaine, and Bouclé, Johann

Subjects
[PHYS.PHYS.PHYS-OPTICS] Physics [physics]/Physics [physics]/Optics [physics.optics], [SPI.NANO] Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, [PHYS.COND.CM-MS] Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci]
Published
2022

27. Niobates ferroelectric thin films: i/ growth and characterization of perovskite and TTB phases in the K-Na-Nb-O system; ii/ potential of application in high frequency miniature tunable devices

Author

Aspe, Barthélemy, Demange, Valérie, Castel, Xavier, Gautier, Brice, Simon, Quentin, Albertini, David, Zaghrioui, Mustapha, Nadaud, Kevin, Députier, Stéphanie, Bouquet, Valérie, Sauleau, Ronan, Guilloux-Viry, Maryline, Institut d'Électronique et des Technologies du numéRique (IETR), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences Chimiques de Rennes (ISCR), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut des Nanotechnologies de Lyon (INL), École Centrale de Lyon (ECL), Université de Lyon-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-École Supérieure de Chimie Physique Électronique de Lyon (CPE)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Université de Tours (UT)-Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Université de Nantes (UN)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), Université de Lyon-École supérieure de Chimie Physique Electronique de Lyon (CPE)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Nantes Université (NU)-Université de Rennes 1 (UR1), Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-École Centrale de Lyon (ECL), Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-École supérieure de Chimie Physique Electronique de Lyon (CPE), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), and Castel, Xavier

Subjects
[SPI.ELEC]Engineering Sciences [physics]/Electromagnetism, [SPI.NANO] Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, [SPI.ELEC] Engineering Sciences [physics]/Electromagnetism, [SPI.MAT] Engineering Sciences [physics]/Materials, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, ComputingMilieux_MISCELLANEOUS, [SPI.MAT]Engineering Sciences [physics]/Materials
Abstract

International audience

Published
2021

28. Perovskite and tetragonal tungsten bronze phase thin films in the K-Na-Nb-O system: structural and dielectric characterizations

Author

Aspe, Barthélemy, Demange, Valérie, Castel, Xavier, Gautier, Brice, Simon, Quentin, Albertini, David, Zaghrioui, Mustapha, Nadaud, Kevin, Députier, Stéphanie, Bouquet, Valérie, Sauleau, Ronan, Guilloux-Viry, Maryline, Institut d'Électronique et des Technologies du numéRique (IETR), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences Chimiques de Rennes (ISCR), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Synthèse Caractérisation Analyse de la Matière (ScanMAT), Université de Rennes (UR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut des Nanotechnologies de Lyon (INL), École Centrale de Lyon (ECL), Université de Lyon-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-École Supérieure de Chimie Physique Électronique de Lyon (CPE)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Université de Tours (UT)-Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Nantes Université (NU)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-École Centrale de Lyon (ECL), Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-École supérieure de Chimie Physique Electronique de Lyon (CPE), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), Université de Nantes (UN)-Université de Rennes 1 (UR1), Université de Lyon-École supérieure de Chimie Physique Electronique de Lyon (CPE)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), and Castel, Xavier

Subjects
[SPI.ELEC]Engineering Sciences [physics]/Electromagnetism, [SPI.NANO] Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, [SPI.ELEC] Engineering Sciences [physics]/Electromagnetism, [SPI.MAT] Engineering Sciences [physics]/Materials, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, ComputingMilieux_MISCELLANEOUS, [SPI.MAT]Engineering Sciences [physics]/Materials
Abstract

International audience

Published
2020

29. Etude des propriétés diélectriques en couches minces d’une nouvelle phase dans le système K-Na-Nb-O pour des applications en hyperfréquences

Author

ASPE, Barthélemy, Demange, Valérie, Castel, Xavier, Simon, Quentin, Zaghrioui, Mustapha, Nadaud, Kevin, Députier, Stéphanie, Gouttefangeas, Francis, Sauleau, Ronan, Guilloux-Viry, Maryline, Institut des Sciences Chimiques de Rennes (ISCR), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut d'Électronique et des Technologies du numéRique (IETR), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Synthèse Caractérisation Analyse de la Matière (ScanMAT), Université de Rennes (UR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Université de Tours (UT)-Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), Université de Nantes (UN)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Castel, Xavier, Nantes Université (NU)-Université de Rennes 1 (UR1), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SPI.ELEC]Engineering Sciences [physics]/Electromagnetism, [SPI.NANO] Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, [SPI.ELEC] Engineering Sciences [physics]/Electromagnetism, [SPI.MAT] Engineering Sciences [physics]/Materials, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, ComputingMilieux_MISCELLANEOUS, [SPI.MAT]Engineering Sciences [physics]/Materials
Abstract

National audience

Published
2020

34. Low-Temperature Hydrothermal Growth of ZnO Nanowires on AZO Substrates for FACsPb(IBr) 3 Perovskite Solar Cells.

Author

Sekar, Karthick, Nakar, Rana, Bouclé, Johann, Doineau, Raphaël, Nadaud, Kevin, Schmaltz, Bruno, and Poulin-Vittrant, Guylaine

Subjects
SOLAR cells, NANOWIRES, ZINC oxide, PEROVSKITE, METALLIC oxides, POROSITY
Abstract

Electron and hole transport layers (ETL and HTL) play an essential role in shaping the photovoltaic performance of perovskite solar cells. While compact metal oxide ETL have been largely explored in planar n-i-p device architectures, aligned nanowires or nanorods remain highly relevant for efficient charge extraction and directional transport. In this study, we have systematically grown ZnO nanowires (ZnO NWs) over aluminum-doped zinc oxide (AZO) substrates using a low-temperature method, hydrothermal growth (HTG). The main growth parameters were varied, such as hydrothermal precursors concentrations (zinc nitrate hexahydrate, hexamethylenetetramine, polyethylenimine) and growing time, in order to finely control NW properties (length, diameter, density, and void fraction). The results show that ZnO NWs grown on AZO substrates offer highly dense, well-aligned nanowires of high crystallinity compared to conventional substrates such as FTO, while demonstrating efficient FACsPb(IBr)3 perovskite device performance, without the requirement of conventional compact hole blocking layers. The device performances are discussed based on NW properties, including void fraction and aspect ratio (NW length over diameter). Finally, AZO/ZnO NW-based devices were fabricated with a recent HTL material based on a carbazole moiety (Cz–Pyr) and compared to the spiro-OMeTAD reference. Our study shows that the Cz–Pyr-based device provides similar performance to that of spiro-OMeTAD while demonstrating a promising stability in ambient conditions and under continuous illumination, as revealed by a preliminary aging test. [ABSTRACT FROM AUTHOR]

Published
2022
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35. Influence of RF Power of ZnO Seed Layer on the Morphological Properties of ZnO Nanowires for Piezoelectric Energy Harvesting

Author

Justeau, Camille, Slimani Tlemcani, Taoufik, Poulin-Vittrant, Guylaine, Nadaud, Kevin, Alquier, Daniel, GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), E-MRS, Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), and Poulin-Vittrant, Guylaine

Subjects
Nanowires, [SPI.NANO] Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, Lattice mismatch, [SPI.NRJ]Engineering Sciences [physics]/Electric power, Hydrothermal synthesis, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, Sputtering power, ZnO seed layer, [SPI.NRJ] Engineering Sciences [physics]/Electric power, Piezoelectric devices
Abstract

International audience; Using a hydrothermal synthesis method, zinc oxide (ZnO) nanowires (NWs) have been grown on ZnO/Au/Ti/Si substrates. This method shows a low temperature (70 °C) approach for growing ZnO NWs on a ZnO seed layer. ZnO films of about 50 nm thickness were deposited by radio frequency (RF) magnetron sputtering at various sputtering powers (150, 100 and 65W). The formation of ZnO seed layers and ZnO NWs was clarified using X-ray diffraction (XRD), and the surface microstructure of the prepared ZnO NWs and ZnO films was characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM), respectively. The results show that the growth behavior of ZnO NWs is strongly impacted by the sputtering power of ZnO seed layers. The decrease of RF sputtering power leads to a diminution in the grain size of ZnO seed layers and a smaller lattice mismatch between seed layers and NWs, thus inducing a morphological improvement and a better alignment of the obtained ZnO NWs. These works aim at optimizing the integration of ZnO NWs for mechanical energy harvesting applications, and to enhance the performance of such piezoelectric devices.

Published
2019

36. Annealing and Thickness Effects of ZnO Seed Layer on Improving Alignment of ZnO NWs for Piezoelectric Nanogenerator Application

Author

Slimani Tlemcani, Taoufik, Justeau, Camille, Nadaud, Kevin, Poulin-Vittrant, Guylaine, Alquier, Daniel, GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), E-MRS, Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), and Poulin-Vittrant, Guylaine

Subjects
hydrothermal synthesis, stretchable nanogenerator, wearable electronics, nanowires, piezoelectric energy harvesters, [SPI.NANO] Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, [SPI.NRJ]Engineering Sciences [physics]/Electric power, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, ZnO seed layer, [SPI.NRJ] Engineering Sciences [physics]/Electric power
Abstract

International audience; Well aligned crystalline zinc oxide (ZnO) nanowires (NWs) on ZnO/Au/Ti/Si substrates were grown by the so-called “hydrothermal synthesis”. ZnO seed layers with different thicknesses ranging from 5 to 100 nm, by controlling the deposition time, were prepared by radio-frequency sputtering followed by a post-annealing treatment in air at 400°C. The effects of deposition time and annealing treatment of ZnO seed layers on the subsequent growth of ZnO NWs were investigated using X-ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM). The experimental results reveal that the quality and growth behavior of ZnO NWs are strongly dependent on both the thickness and the heat treatment of the ZnO seed layers. This work is an optimization step of the facile, cost-effective and industrially scalable process flow recently developed for the fabrication of a high performance nanocomposite-based stretchable nanogenerator (SNG) on polydimethylsiloxane (PDMS) substrate. The morphological improvement of hydrothermally grown ZnO NWs may therefore lead to higher performance SNGs for the targeted application of mechanical energy harvesting in order to supply flexible and wearable electronics.

Published
2019

37. Challenges of low-temperature synthesized ZnO nanowires and their integration into nanogenerators

Author

Justeau, Camille, Dahiya, Abhishek Singh, Nadaud, Kevin, Boubenia, Sarah, Slimani Tlemcani, Taoufik, Chandraiahgari, Chandrakanth Reddy, Alquier, Daniel, Poulin-Vittrant, Guylaine, GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), Poulin-Vittrant, Guylaine, and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SPI.NANO] Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, [SPI.NRJ]Engineering Sciences [physics]/Electric power, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, [SPI.NRJ] Engineering Sciences [physics]/Electric power
Abstract

International audience; From the multitude of nanostructures under active research, Zinc Oxide (ZnO) nanowires (NWs) have attracted enormous attention due to the materials’ unique electrical, optical, mechanical and piezoelectric properties. Since 10 years, piezoelectric nanocomposites based nanogenerators (NGs) have gained extensive attention for their applications in mechanical energy harvesters and self-powered tactile sensors. Hydrothermal approach is used for the synthesis of ZnO NWs and is a low cost manufacturing process, compatible with large area substrates. We present here a flexible and stretchable nanogenerator (SNG) which is manufactured thanks to a facile, cost-effective and industrially scalable process, on a polydimethylsiloxane (PDMS) substrate. The SNG exhibits excellent performance with a 35 μW peak output power achieved from a 8 cm2 device under a pressure of 100 kPa. The key issues of efficient NGs will be presented, in order to maximize the performance of these devices dedicated to low frequency mechanical energy harvesting.

Published
2019

38. Influence of the synthesis parameters on hydrothermally grown ZnO nanowires dedicated to mechanical energy harvesting

Author

Slimani Tlemcani, Taoufik, Justeau, Camille, Nadaud, Kevin, Poulin-Vittrant, Guylaine, Alquier, Daniel, GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), and Poulin-Vittrant, Guylaine

Subjects
[SPI.NANO] Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, [SPI.NRJ]Engineering Sciences [physics]/Electric power, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, [SPI.NRJ] Engineering Sciences [physics]/Electric power
Abstract

International audience; We demonstrate that vertical well-aligned crystalline ZnO nanowires (NWs) arrays were grown on ZnO/Au/Ti/Si substrates by a hydrothermal method. Different thicknesses of ZnO seed layers were prepared by radio-frequency sputtering followed by a post-annealing treatment in air at 400°C. The effects of deposition time and annealing treatment of ZnO seed layers on the subsequent growth of ZnO NWs were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). In this work it was found that the morphology of ZnO NWs strongly depends on both the thickness and the heat treatment of the ZnO seed layers. The improved control of the morphology of ZnO nanowire arrays may lead to an enhanced performance of the resulting piezoelectric energy harvesting devices based on ZnO.

Published
2019

39. Nanogénérateurs à base d'oxyde de zinc et de parylène C pour la récupération d'énergie mécanique basse fréquence

Author

Justeau, Camille, Slimani Tlemcani, Taoufik, Dahiya, Abhishek Singh, Boubenia, Sarah, Morini, François, Nadaud, Kevin, Poulin-Vittrant, Guylaine, Alquier, Daniel, GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), and Poulin-Vittrant, Guylaine

Subjects
Nanofils de ZnO, [SPI.NANO] Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, Nanogénérateur, [SPI.NRJ]Engineering Sciences [physics]/Electric power, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, Flexible, [SPI.NRJ] Engineering Sciences [physics]/Electric power, Piézoélectricité
Abstract

International audience; Les préoccupations liées à la récupération et à la conservation de l’énergie pour aider au développement de réseaux microélectroniques autonomes sont aujourd’hui au coeur des problématiques de recherche. Le développement des techniques de récupération d’énergie basées sur la thermoélectricité, le solaire ou l’éolien, cherchant à répondre aux enjeux énergétiques actuels, font cependant face à de nombreuses limitations, notamment la disponibilité intermittente de la source d’énergie. Par ailleurs, depuis plusieurs années, le développement de récupérateurs d’énergie mécanique attire l’attention des chercheurs du fait de la disponibilité de cette énergie dans l’environnement humain ou industriel. Ainsi, différents systèmes ont vu le jour en s’appuyant notamment sur les principes de triboélectricité [1] et de piézoélectricité [2]. Dans ce contexte, les nanogénérateurs (NGs) piézoélectriques [3], développés à partir d’une matrice composite de nanofils (NFs) de ZnO et de parylène, présentent aujourd’hui un grand potentiel pour la récupération d’énergie. La structure 1D des NFs de ZnO, matériau piézoélectrique, permet un accroissement de la sensibilité aux faibles sollicitations mécaniques [4] et laisse présager des performances électriques intéressantes lorsque intégrés dans les dispositifs de récupération d’énergie. Les caractéristiques prometteuses de ce matériau, alliées à sa non toxicité pour l’environnement ainsi qu’à la facilité des étapes de fabrication du NG, font de ce système un candidat idéal à l’industrialisation de ce type de générateur piézoélectrique.Nous présentons dans ce poster le développement et les performances associées à l’intégration des NFs de ZnO synthétisés par croissance hydrothermale [5] et encapsulés dans du parylène pour la fabrication de NGs piézoélectriques. Cette étude vise à la fois à l’amélioration des performances des NGs et à l’optimisation de leur design pour différentes applications.Références[1] Y. Yang, G. Zhu, H. Zhang, J. Chen, X. Zhong, ZH. Lin, Y. Su, P. Bai, X. Wen, et Z.L. Wang (2013) « Triboelectric Nanogenerator for Harvesting Wind Energy and as Self Powered Wind Vector Sensor System », ASC Nano, 7 (10), pp. 9461-9468.[2] Z.L. Wang, X. Wang, J. Song, J. Liu, et Y. Gao, (2008), « Piezoelectric nanogenerators for sel-powered nanodevices », IEE, 7(1), pp. 49-55.[3] Z. L. Wang, J. Song (2016) « Piezoelectric Nanogenerators Based on Zinc Oxide Nanowire Arrays », Science, 312 (5771), pp. 242-246.[4] Z.L. Wang (2008) « Towards self-powered nanosystems: From nanogenerators to nanopiezotronics », Advanced Functional Materials, 18, pp.3553–3567.[5] S. Boubenia, A.S. Dahiya, G. Poulin-Vittrant, F. Morini, K. Nadaud, D. Alquier (2017) « A facile hydrothermal approach for the density tunable growth of ZnO nanowires and their electrical characterizations », Scientific Reports, 7, pp. 1-10.

Published
2019

40. Effect of thermal annealing on dielectric and ferroelectric properties of aerosol-deposited 0.65Pb(Mg1/3Nb2/3)O3-0.35PbTiO3 thick films.

Author

Nadaud, Kevin, Sadl, Matej, Bah, Micka, Levassort, Franck, and Ursic, Hana

Subjects
DIELECTRIC properties, THICK films, LEAD zirconate titanate films, POLARIZATION (Electricity), ELECTRIC fields, IMPEDANCE spectroscopy, PERMITTIVITY
Abstract

In this work, the effects of thermal annealing at 500 °C on aerosol-deposited 0.65Pb(Mg1/3Nb2/3)O3-0.35PbTiO3 thick films on stainless-steel substrates are investigated using two complementary methods at high and low applied external electric fields. The first one is the positive up negative down method, which allows us to obtain information about the switching and non-switching contributions to the polarization. It shows that the as-deposited film is ferroelectric before annealing, since it has a switching contribution to the polarization. After annealing, both the switching and non-switching contributions to polarization increased by a factor of 1.6 and 2.33, respectively, indicating a stronger ferroelectric behavior. The second method is based on impedance spectroscopy coupled with Rayleigh analysis. The results show that post-deposition thermal annealing increases the reversible domain wall contribution to the dielectric permittivity by a factor of 11 while keeping the threshold field similar. This indicates that, after annealing, domain wall density is larger while domain wall mobility remains similar. These two complementary characterization methods show that annealing increases the ferroelectric behavior of the thick film by increasing the domain wall density, and its influence is visible both on polarization vs electric field loop and dielectric permittivity. [ABSTRACT FROM AUTHOR]

Published
2022
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41. Decomposition of the different contributions to permittivity, losses, and tunability in BaSrTiO3 thin films using the hyperbolic law.

Author

Nadaud, Kevin, Borderon, Caroline, Renoud, Raphaël, and Gundel, Hartmut W.

Subjects
*THIN film research, *MANGANESE, *SEMICONDUCTOR doping, *DOPED semiconductors, *PERMITTIVITY
Abstract

In this paper, the different contributions to the permittivity of a 1% manganese-doped BaSrTiO3 thin film are presented as a function of the applied DC field. The hyperbolic law has been used to discern the lattice, domain wall vibration, and pinning/unpinning contributions. This decomposition permits us to study the weight of the respective contribution in the total permittivity, the losses, and the tunability. By determining the figure of merit (FoM) of each contribution, the ratio between tunability and losses, it is possible to identify the phenomenon which should be limited or enhanced in order to optimize the material's dielectric properties. It is shown that the tunability of the domain wall contribution (approximately 80%) is very important compared to the lattice contribution (41%), the associated dissipation factor, however, is also much larger (0.2 instead of 0.014). Even if the domain wall contribution has been shown to be weak in the investigated thin film (less than 3% in permittivity and tunability), the weight of the losses is not negligible (around 18%). Hence, the domain contribution has to be limited in order to conserve a high FoM for the material. Moreover, it is shown that the AC field used for the material's characterization is important because it governs the weight of the domain wall losses and thus the FoM. [ABSTRACT FROM AUTHOR]

Published
2016
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42. PLD growth of tetragonal tungsten bronze phase thin films in the K-Na-Nb-O system: structural and dielectric characterizations

Author

ASPE, Barthélemy, Demange, Valérie, Castel, Xavier, Simon, Quentin, Zaghrioui, Mustapha, Nadaud, Kevin, Députier, Stéphanie, Gouttefangeas, Francis, Sauleau, Ronan, Guilloux-Viry, Maryline, Castel, Xavier, Institut des Sciences Chimiques de Rennes (ISCR), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), Institut d'Électronique et des Technologies du numéRique (IETR), Université de Nantes (UN)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Synthèse Caractérisation Analyse de la Matière (ScanMAT), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Université de Tours (UT)-Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Université de Rennes (UR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Nantes Université (NU)-Université de Rennes 1 (UR1), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SPI.ELEC]Engineering Sciences [physics]/Electromagnetism, [SPI.NANO] Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, [SPI.ELEC] Engineering Sciences [physics]/Electromagnetism, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, [SPI.MAT] Engineering Sciences [physics]/Materials, ComputingMilieux_MISCELLANEOUS, [SPI.MAT]Engineering Sciences [physics]/Materials
Abstract

International audience

Published
2019

43. Influence des paramètres de synthèse hydrothermale sur les nanofils de ZnO pour leur intégration dans des nanogénérateurs piézoélectriques

Author

Slimani Tlemcani, Taoufik, Justeau, Camille, Nadaud, Kevin, Poulin-Vittrant, Guylaine, Alquier, Daniel, Poulin-Vittrant, Guylaine, GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SPI.NANO] Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, [SPI.NRJ]Engineering Sciences [physics]/Electric power, Nanogénérateurs piézoélectriques, ZnO, Synthèse hydrothermale, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, Nanofils, [SPI.NRJ] Engineering Sciences [physics]/Electric power
Abstract

International audience; La récupération d’énergie mécanique grâce aux NanoGénérateurs PiézoElectriques (PENGs) suscite depuis 2006 [1] un intérêt croissant pour le développement de microsystèmes autonomes. Les PENGs sont des composites intégrant des nanofils piézoélectriques, le plus souvent en oxyde de zinc ZnO ou en nitrure de gallium GaN (qui sont tous deux également semi-conducteurs), enrobés d’une matrice généralement constituée d’un matériau diélectrique souple. L'optimisation du matériau piézoélectrique nanostructuré, notamment sa morphologie (diamètre et longueur, celle-ci étant généralement de l’ordre du µm), sa densité (nombre de nanofils par unité de surface) et sa qualité (défauts structurels pouvant entraîner un dopage semiconducteur intrinsèque), est cruciale pour l'amélioration des performances des dispositifs PENGs. En effet, il a été démontré que le potentiel électrique et l'efficacité des dispositifs PENGs dépendent fortement de la morphologie du nanofil, qui affecte à la fois ses propriétés électriques et mécaniques [1], et dépendent également de la densité des nanofils [2]. Dans cette étude, nous nous sommes concentrés sur l’élaboration de nanofils de ZnO de dimensions contrôlées en utilisant la technique hydrothermale. La morphologie des nanofils a été contrôlée en agissant sur la sous couche de ZnO. Nous avons montré, en effectuant la synthèse de nanofils sur des sous couches de ZnO de différentes épaisseurs, que l’épaisseur de la sous couche influence nettement les propriétés des nanofils obtenus, de même qu’un traitement thermique effectué sur la sous couche avant la croissance des nanofils (Figure 1). Les propriétés structurales et morphologiques des nanofils obtenus avec ces différentes conditions de synthèse ont été étudiées par diffraction des rayons X et microscopie électronique à balayage (MEB). Finalement, pour chaque type de sous couche expérimentée, des dispositifs PENGs, constitués de ZnO (sous couche)/ZnO (nanofils)/Parylène, ont été fabriqués et caractérisés. Cela nous a permis de mieux comprendre les mécanismes électriques impliqués dans ce type de dispositif, ouvrant de nombreuses possibilités pour améliorer leurs performances.Références[1] Z. L. Wang, J. Song, « Piezoelectric Nanogenerators Based on Zinc Oxide Nanowire Arrays », Science 2006, 312, 242-246. [2] A. Rinaldi, R. Araneo, S. Celozzi, M. Pea et A. Notargiacomo, « The clash of mechanical and electrical size-effects in ZnO nanowires and a double power law approach to elastic strain engineering of piezoelectric and piezotronic devices », Adv. Mater., 2014, 5976–5985.[3] R. Tao, M. Parmar, G. Ardila, P. Oliveira et D. Marques, « Performance of ZnO based piezo-generators under controlled compression », Semicond. Sci. Technol.,2017, 32, 64003.

Published
2019

44. Numerical approach to design efficient mechanical energy harvesting system based on piezo-semiconducting nanowires

Author

Boubenia, Sarah, Doumit, Nicole, Nadaud, Kevin, Alquier, Daniel, Poulin-Vittrant, Guylaine, Poulin-Vittrant, Guylaine, GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SPI.NANO] Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, [SPI.NRJ]Engineering Sciences [physics]/Electric power, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, [SPI.NRJ] Engineering Sciences [physics]/Electric power
Abstract

International audience; Nanoscale mechanical energy harvesting using PiezoElectric NanoGenerators (PENGs) has been highlightedas a potential candidate for the realization of self-powered biomedical devices such as pacemakers andwearable communication devices. A PENG can be described as a stack of five layers (Figure 1) : a rigid orflexible substrate, a bottom electrode, an electroactive layer (piezoelectric semiconducting nanowires (NWs)surrounded by an insulating polymer), a top layer of insulating material and a top electrode [1]. For thecontinual performance improvement of PENG devices, optimization of the piezoelectric semiconductingnanomaterial, including morphology, density and quality, is of great interest and crucial. For example, it hasbeen theoretically shown that the output potential and efficiency of PENGs strongly depend on the electricalquality of the nanomaterial [2]. Among several nanomaterials, zinc oxide (ZnO) NWs can be synthesized byhydrothermal method, which is low temperature, industrially scalable and compatible with flexible substrates[3]. Different approaches have been used to model ZnO NW based PENGs including analytical models andnumerical models using finite element method (FEM) [1].In the present work, COMSOL software is used to model ZnO NW based PENGs. First, the piezoelectricpotential distribution in ZnO NWs is studied for different intrinsic doping concentrations. In terms ofpiezopotential magnitude, cylindrical shaped NWs with low doping completely outperformed their homologueNWs being highly doped leading to significant piezoelectric potential screening effect. Figure 2 shows that, atthe applied static pressure of 6.25 MPa, a cylindrical NW with a 1010 (/cm3) charge density presents amaximum piezoelectric potential of 2.9 V compared to 0.25 V reached by a 1015 (/cm3) doped NW. Moreover,in order to predict the complete PENG electrical characteristics and to reduce computation time, a newapproach using FEM simulation and analytical modelling has been developed [1]. This method combines FEMsimulation of a PENG unit cell (including one NW) in order to estimate the open-circuit voltage (without anyexternal electrical circuit), and an analytical model of the full PENG in order to predict the maximum powerand the corresponding optimal load. Further works will consist in studying the effect of the geometricalcharacteristics and electromechanical properties of the nanowire-polymer composite on the complete PENGperformance.References[1] Doumit N and Poulin-Vittrant G 2018 A new simulation approach for performance prediction ofvertically integrated nanogenerators Adv. Theory Simul. 1800033 1–8[2] Gao Y and Wang Z L 2009 Equilibrium potential of free charge carriers in a bent piezoelectricsemiconductive nanowire Nano Lett. 9 1103–10[3] Dahiya A S, Morini F, Boubenia S, Nadaud K, Alquier D, Poulin-Vittrant G 2017 Organic / inorganichybrid stretchable piezoelectric nanogenerators for self-powered wearable electronics AdvancedMaterials Technologies 1700249 11 pp.

Published
2019

47. Effect of manganese doping of BaSrTiO3 on diffusion and domain wall pinning.

Author

Nadaud, Kevin, Borderon, Caroline, Renoud, Raphaël, and Gundel, Hartmut W.

Subjects
*MANGANESE, *SEMICONDUCTOR doping, *DIELECTRIC properties, *THIN films, *ELECTRIC fields
Abstract

In the present paper, the influence of manganese doping on the dielectric properties of BaSrTiO3 thin films is presented. The real and imaginary parts of the material's permittivity have been measured in a large frequency range (100 Hz-1 MHz) and as a function of the electric field. The tunability and the figure of merit of the material have been obtained from the measurement of the permittivity under an applied DC bias electric field. For the undoped material, the dielectric losses become important for a large DC bias which leads to breakdown. At a suitable dopant rate, this effect disappears. In order to better understand the origin of the related phenomena, we measure the permittivity as a function of the AC excitation amplitude and we decompose the obtained permittivity with the hyperbolic law. This enables to extract the different contributions of the bulk (low frequency diffusion and high frequency lattice relaxation) and of the domain wall motions (vibration and pinning/unpinning) to the material's dielectric permittivity and to understand the effect of manganese doping on each contribution. Knowledge of the related mechanisms allows us to establish the optimum dopant rate (mainly conditioned by the lattice contribution) and to reduce the domain wall motion, which finally is beneficial for the desired properties of the ferroelectric thin film. A particular attention is paid to low frequency diffusion, an especially harmful effect when a DC biasing is mandatory (tunable electronic component in mobile telecommunication devices for example). [ABSTRACT FROM AUTHOR]

Published
2015
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48. Co-conception material microwave: study and realization of tunable BST thin film for reflectarray applications

Author

Nadaud, Kevin, Institut d'Électronique et des Technologies du numéRique (IETR), Nantes Université (NU)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), CNRS-INSIS, Région Pays de la Loire, Université de Nantes, Hartmut W. Gundel, Raphaël Gillard, Caroline Borderon, Université de Nantes (UN)-Université de Rennes 1 (UR1), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), and Nadaud, Kevin

Subjects
impedance spectroscopy, domain walls, parois de domaines, cellule déphaseuse, Couches minces ferroélectriques, Ferroelectric thin films, reconfigurabilité, [SPI.TRON] Engineering Sciences [physics]/Electronics, [SPI.TRON]Engineering Sciences [physics]/Electronics, phase-shifting cell, spectroscopie d'impédance, reflectarray, tunability, BST, réseaux réflecteurs
Abstract

Nowadays, wireless systems have to be able to adapt to different environments and standards, requiring reconfigurable microwave devices in order to dynamically vary their characteristics. Among all possible technological solutions to achieve this reconfigurability, agile materials, more specifically ferroelectrics, have an increasing interest. The major advantages compared to other technologies are a low bias current and the absence of moving parts.This manuscript presents the optimization and characterization of BaSrTiO3 (BST) ferroelectric thin films elaborated by chemical solution deposition. The complex permittivity was measured as a function of frequency, temperature, DC and AC fields. The fundamental study by impedance spectroscopy allows describing the relations between the structural microscopic properties (doping, grain size, defects, etc.) and the different permittivity contributions, including domain wall motion. This also helps to better understand the origin of the tunability and the dielectric losses in the material.The developed thin films were used for the realization of reconfigurable reflectarray cells, optimized by parametric studies. Two cell versions having increasing complexity and performance have been designed, realized and measured. Cell modeling also helped to develop an equivalent circuit, suitable for fast and efficient optimization of dimensions. The results indicate that the BST is a valuable candidate for this kind of application., Un système sans fil doit dorénavant s’adapter à des environnements et des standards variés, ce qui demande des dispositifs hyperfréquences reconfigurables pour faire varier dynamiquement leurs caractéristiques. Parmi toutes les solutions technologiques possibles pour permettre cette reconfiguration, les matériaux agiles, et plus particulièrement les ferroélectriques, suscitent un intérêt croissant. Leurs avantages majeurs sont un faible courant de polarisation et l'absence de pièces en mouvement.Ce manuscrit présente l'optimisation et la caractérisation de couches minces ferroélectriques de BaSrTiO3 (BST) déposées par voie chimique (procédé sol-gel). La mesure de la permittivité complexe a été effectuée en fonction de la fréquence, de la température et des champs DC et AC. L'étude fondamentale par spectroscopie d'impédance permet de décrire les liens entre les propriétés structurales (dopage, taille de grains, défauts, etc.) et les différentes contributions à la permittivité et notamment les mouvements des parois de domaines. Ceci permet également de mieux comprendre l'origine de l'accordabilité et des pertes diélectriques dans ce matériau. Les couches minces élaborées ont été utilisées pour la réalisation de cellules pour réseau réflecteur reconfigurable, optimisées à l'aide d'une étude paramétrique. Deux versions de cellules, de complexité et de performances croissantes, ont été conçues, réalisées et mesurées. La modélisation des cellules a également permis de mettre au point un schéma équivalent, exploitable pour une optimisation rapide et efficace des dimensions. Les résultats obtenus indiquent que le BST est un candidat sérieux pour ce type d'applications.

Published
2015

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