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18228
01/11/2018

Fano-Resonances in High Index Dielectric Nanowires for Directional Scattering

P.WIECHA, A.CUCHE, H.KALLEL, G.COLAS DES FRANCS, A.LECESTRE, G.LARRIEU, V.LARREY, F.FOURNEL, T.BARON, A.ARBOUET, V.PAILLARD

CEMES/CNRS, LICB, TEAM, MPN, CEA-LETI, LTM

Ouvrage (contribution) : Fano Resonances in Optics and Microwaves, Springer, N°ISBN 978-3-319-99730-8, Novembre 2018, 29p. , N° 18228

Lien : https://hal.archives-ouvertes.fr/hal-01850259

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Abstract

High refractive index dielectric nanostructures provide original optical properties thanks to the occurrence of size- and shape-dependent optical resonance modes. These modes commonly present a spectral overlap of broad, low-order modes (\textit{e.g}. dipolar modes) and much narrower, higher-order modes. The latter are usually characterized by a rapidly varying frequency-dependent phase, which - in superposition with the lower order mode of approximately constant phase - leads to typical spectral features known as Fano resonances. Interestingly, such Fano resonances occur in dielectric nanostructures of the simplest shapes. In spheroidal nanoparticles, interference between broad magnetic dipole and narrower electric dipole modes can be observed. In high aspect-ratio structures like nanowires, either the electric or the magnetic dipolar mode (depending on the illumination conditions) interferes with higher order multipole contributions of the same nature (electric or magnetic). Using the analytical Mie theory, we analyze the occurrence of Fano resonances in high-index dielectric nanowires and discuss their consequences like unidirectional scattering. By means of numerical simulations, we furthermore study the impact on those Fano resonances of the shape of the nanowire cross-sections as well as the coupling of two parallel nanowires. The presented results show that all-dielectric nanostructures, even of simple shapes, provide a reliable low-loss alternative to plasmonic nanoantennas.

144273
18294
09/10/2018

Growth of InAs and Bi1-xSbx Nanowires on Silicon for Nanoelectronics and Topological Qubits by Molecular Beam Epitaxy

D.DHUNGANA

MPN

Doctorat : Université de Toulouse III - Paul Sabatier, 9 Octobre 2018, 174p., Président: F.CRISTIANO, Rapporteurs: A.LEMAITRE, E.P.A.M.BAKKERS, Examinateurs: Y.ANDRE, Directeurs de thèse: S.PLISSARD , N° 18294

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Résumé

Grâce à leur propriétés uniques, les nanofils d’InAs et de Bi1-xSbx sont important pour les domaines de la nanoélectronique et de l’informatique quantique. Alors que la mobilité électronique de l’InAs est intéressante pour les nanoélectroniques; l’aspect isolant topologique du Bi1-xSbx peut être utilisé pour la réalisation de Qubits basés sur les fermions de Majorana. Dans les deux cas, l’amélioration de la qualité du matériau est obligatoire et ceci est l’objectif principal cette thèse où nous étudions l’intégration des nanofils InAs sur silicium (compatibles CMOS) et où nous développons un nouvel isolant topologique nanométrique: le Bi1-xSbx. Pour une compatibilité CMOS complète, la croissance d’InAs sur Silicium nécessite d’être autocatalysée, entièrement verticale et uniforme sans dépasser la limite thermique de 450 ° C. Ces normes CMOS, combinées à la différence de paramètre de maille entre l’InAs et le silicium, ont empêché l’intégration de nanofils InAs pour les dispositifs nanoélectroniques. Dans cette thèse, deux nouvelles préparations de surface du Si ont été étudiées impliquant des traitements Hydrogène in situ et conduisant à la croissance verticale et auto-catalysée de nanofils InAs compatible avec les limitations CMOS. Les différents mécanismes de croissance résultant de ces préparations de surface sont discutés en détail et un passage du mécanisme Vapor-Solid (VS) au mécanisme Vapor- Liquid-Solid (VLS) est rapporté. Les rapports d’aspect très élevé des nanofils d’InAs sont obtenus en condition VLS: jusqu’à 50 nm de diamètre et 3 microns de longueur. D’autre part, le Bi1-xSbx est le premier isolant topologique 3D confirmé expérimentalement. Dans ces nouveaux matériaux, la présence d’états surfacique conducteurs, entourant le coeur isolant, peut héberger les fermions de Majorana utilisés comme Qubits. Cependant, la composition du Bi1-xSbx doit être comprise entre 0,08 et 0,24 pour que le matériau se comporte comme un isolant topologique. Nous rapportons pour la première fois la croissance de nanofils Bi1-xSbx sans défaut et à composition contrôlée sur Si. Différentes morphologies sont obtenues, y compris des nanofils, des nanorubans et des nanoflakes. Leur diamètre peut être de 20 nm pour plus de 10 microns de long, ce qui en fait des candidats idéaux pour des dispositifs quantiques. Le rôle clé du flux Bi, du flux de Sb et de la température de croissance sur la densité, la composition et la géométrie des structures à l’échelle nanométrique est étudié et discuté en détail.

Abstract

InAs and Bi1-xSbx nanowires with their distinct material properites hold promises for nanoelectronics and quantum computing. While the high electron mobility of InAs is interesting for nanoelectronics applications, the 3D topological insulator behaviour of Bi1-xSbx can be used for the realization of Majorana Fermions based qubit devices. In both the cases improving the quality of the nanoscale material is mandatory and is the primary goal of the thesis, where we study CMOS compatible InAs nanowire integration on Silicon and where we develop a new nanoscale topological insulator. For a full CMOS compatiblity, the growth of InAs on Silicon requires to be self-catalyzed, fully vertical and uniform without crossing the thermal budge of 450 °C. These CMOS standards, combined with the high lattice mismatch of InAs with Silicon, prevented the integration of InAs naowires for nanoelectronics devices. In this thesis, two new surface preparations of the Silicon were studied involving in-situ Hydrogen gas and in-situ Hydrogen plasma treatments and leading to the growth of fully vertical and self-catalyzed InAs nanowires compatible with the CMOS limitations. The different growth mechanisms resulting from these surface preparations are discussed in detail and a switch from Vapor-Solid (VS) to Vapor-Liquid-Solid (VLS) mechanism is reported. Very high aspect ratio InAs nanowires are obtained in VLS condition: upto 50 nm in diameter and 3 microns in length. On the other hand, Bi1-xSbx is the first experimentally confirmed 3D topololgical insulator. In this new material, the presence of robust 2D conducting states, surrounding the 3D insulating bulk can be engineered to host Majorana fermions used as Qubits. However, the compostion of Bi1-xSbx should be in the range of 0.08 to 0.24 for the material to behave as a topological insulator. We report growth of defect free and composition controlled Bi1-xSbx nanowires on Si for the first time. Different nanoscale morphologies are obtained including nanowires, nanoribbons and nanoflakes. Their diameter can be 20 nm thick for more than 10 microns in length, making them ideal candidates for quantum devices. The key role of the Bi flux, the Sb flux and the growth temperature on the density, the composition and the geometry of nanoscale structures is investigated and discussed in detail.

144673
18266
01/10/2018

Liquid crystal-based tunable photodetector operating in the telecom C-band

C.LEVALLOIS, B.SADANI, B.BOISNARD, T.CAMPS, C.PARANTHOEN, S.PES, S.BOUCHOULE, L.DUPONT, J.B.DOUCET, M.ALOUINI, V.BARDINAL

INSA Rennes, MICA, FOTON, C2N, TEAM

Revue Scientifique : Optics Express, Vol.26, N°20, pp.25952-25961, Octobre 2018 , N° 18266

Lien : https://hal.archives-ouvertes.fr/hal-01879162

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Abstract

Liquid crystal (LC) microcells monolithically integrated on the surface of InGaAs based photodiodes (PDs) are demonstrated. These LC microcells acting as tunable Fabry-Perot filters exhibit a wavelength tunability of more than 100 nm around 1550 nm with less than 10V applied voltage. Using a tunable laser operating in the S and C bands, photocurrent measurements are performed. On a 70 nm tuning range covered with a driving voltage lower than 7V, the average sensitivity for the PD is 0.4 A/W and the spectral linewidth of the LC filter remains constant, showing a FWHM of 1.5 nm. Finally, the emission spectrum from an Er-doped fiber is acquired by using this tunable PD as a micro-spectrometer.

144558
18188
21/09/2018

Nanosecond laser defects induced in crystalline silicon annealed: identification, localization and electrical impact

R.MONFLIER, H.RIZK, T.TABATA, J.ROUL, E.IMBERNON, S.BONINELLI, M.ITALIA, A.LA MAGNA, F.MAZZAMUTO, P.ACOSTA ALBA, S.KERDILES, F.CRISTIANO

MPN, SCREEN-LASSE, I2C, TEAM, CNR-IMM, Catania, CEA-LETI

Manifestation avec acte : International Conference on Ion Implantation Technology ( IIT ) 2018 du 16 septembre au 21 septembre 2018, Wurzburg (Allemagne), Septembre 2018, 1p. , N° 18188

Lien : https://hal.laas.fr/hal-01803955

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Abstract

Laser Thermal Annealing (LTA) in conjunction with ion implantation has been demonstrated to be a very effective method to achieve heavily doped and localized regions needed in both advanced MOSFET and solar cells technology. In some cases, degradation of the electrical properties of the laser doped regions has been reported, including increased leakage current in p-n junctions, reduced carrier mobility and breakdown voltage shift in MOS transistors or reduced carrier lifetime in solar cells, which are attributed to laser-induced damage, including impurity penetration during anneal or point defect generation during melt recrystallization. In this work, we present a comprehensive investigation of laser induced damage by implementing a methodology allowing the identification and the localization of the defects as well as the investigation of their impact on the properties of the annealed regions.

144021
18305
23/08/2018

Liquid crystal based tunable PIN-photodiodes for detection around 1.55-µm

C.LEVALLOIS, C.PARANTHOEN, B.BOISNARD, T.CAMPS, B.SADANI, S.PES, S.BOUCHOULE, L.DUPONT, J.B.DOUCET, M.ALOUINI, V.BARDINAL

INSA Rennes, MICA, FOTON, C2N, TEAM

Manifestation avec acte : SPIE Nanoscience + Engineering ( ) 2018 du 19 août au 23 août 2018, San Diego (USA), Août 2018, 7p. , N° 18305

Lien : https://hal.archives-ouvertes.fr/hal-01879173

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Abstract

In this work, we report InGaAs based photodiodes integrating liquid crystal (LC) microcells resonant microcavity on their surface. The LC microcavities monolithically integrated on the photodiodes act as a wavelength selective filter for the device. Photodetection measurements performed with a tunable laser operating in the telecom S and C bands demonstrated a wavelength sweep for the photodiode from 1480 nm to 1560 nm limited by the tuning range of the laser. This spectral window is covered with a LC driving voltage of 7V only, corresponding to extremely low power consumption. The average sensitivity over the whole spectral range is 0.4 A/W, slightly lower than 0.6 A/W for similar photodiodes that do not integrate such a LC tunable filter. The quality of the filter integrated onto the surfaces of the photodiodes is constant over a large tuning range (70 nm), showing a FWHM of 1.5 nm.

144750
18227
20/08/2018

Pushing the limits of optical information storage using deep learning

P.WIECHA, A.LECESTRE, N.MALLET, G.LARRIEU

CEMES/CNRS, TEAM, MPN

Rapport LAAS N°18227, Août 2018, 10p.

Lien : https://hal.archives-ouvertes.fr/hal-01850258

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Abstract

Diffraction drastically limits the bit density in optical data storage. To increase the storage density, alternative strategies involving supplementary recording dimensions and robust read-out schemes must be explored. Here, we propose to encode multiple bits of information in the geometry of subwavelength dielectric nanostructures. A crucial problem in high-density information storage concepts is the robustness of the information readout with respect to fabrication errors and experimental noise. Using a machine-learning based approach in which the scattering spectra are analyzed by an artificial neural network, we achieve quasi error free read-out of 4-bit sequences, encoded in top-down fabricated silicon nanostructures. The read-out speed can further be increased exploiting the RGB values of microscopy images, and the information density could be increased beyond current state of the art. Our work paves the way towards high-density optical information storage using planar silicon nanostructures, compatible with mass-production ready CMOS technology.

144261
18177
01/08/2018

Direct patterning of polymer optical periodic nanostructures on CYTOP for visible light waveguiding

M.DIEZ GARCIA, V.RAIMBAULT, S.JOLY, L.OYHENART, J.B.DOUCET, I.OBIETA, C.DEJOUS, L.BECHOU

IMS Bordeaux, MICA, TEAM, Tecnalia Research & Innovation

Revue Scientifique : Optical Materials, Vol.82, pp.21-29, Août 2018 , N° 18177

Lien : https://hal.archives-ouvertes.fr/hal-01825019

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Abstract

Optical waveguides and grating couplers based on polymer nanostructures are now considered as promising technologies for integrated biophotonic sensing systems. Commonly, structuration and patterning of polymers at the submicron scale requires the use of time and cost-consuming equipments such as electron beam lithography. Direct patterning of high refractive index polymer devices on CYTOP is now achievable and provides symmetric waveguides with top water-like claddings. In addition, transparency of polymers makes them suitable for operation in the visible range, being of major interest for biophotonic applications. In this paper, we report on the fabrication process of polymer submicronic single-mode waveguides on CYTOP for visible light operation. Subwavelength grating couplers with a pitch lower than 300 nm were fabricated to couple the input light into a 350 nm square cross-section waveguide. The whole device is imprinted in a single step using soft stamp lithography with a minimal residual layer. Finally, optical characterizations demonstrate a state-of-the-art transmission efficiency (around 1.5%) at the selected operating wavelength of 507 nm for different coupling angles in good agreement with simulations.

143933
18210
01/08/2018

Liquid-Crystal alignment by a nanoimprinted grating for wafer-scale fabrication of tunable devices

B.SADANI, B.BOISNARD, X.LAFOSSE, T.CAMPS, J.B.DOUCET, E.DARAN, C.PARANTHOEN, C.LEVALLOIS, L.DUPONT, S.BOUCHOULE, V.BARDINAL

MICA, LPN, TEAM, INSA Rennes, C2N

Revue Scientifique : IEEE Photonics Technology Letters, Vol.30, N°15, pp.1388-1391, Août 2018 , N° 18210

Lien : https://hal.laas.fr/hal-01839878

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Abstract

A simple technology is demonstrated for wafer-scale fabrication of liquid-crystal (LC) microcells that can be integrated in active optoelectronic devices. Fabrication of 1.55µm tunable Fabry-Perot optical micro-filter arrays is achieved owing to the insertion of a single nanoimprinted polymer grating dedicated to LC alignment and to the soft thermal transfer of a dry thick resist film between two highly reflective mirrors. The filter exhibits a spectral tuning range of 102nm with only 18V applied, as well as negligible internal loss, which makes it suitable for being inserted in a laser cavity. This constitutes a key step toward large-scale integration of widely-tunable photonic devices such as VCSELs using LC technology.

144201
18283
01/08/2018

Direct laser fabrication of meso-scale 2D and 3D architectures with micrometric feature resolution

A.ACCARDO, R.COURSON, R.RIESCO ALVAREZ, V.RAIMBAULT, L.MALAQUIN

ELIA, TEAM, MEMS, MICA

Revue Scientifique : Additive Manufacturing, Vol.22, pp.440-446, Août 2018 , N° 18283

Lien : https://hal.laas.fr/hal-01875364

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Abstract

The realization of 2D and 3D meso-scale architectures is an area of research involving a wide range of disciplines ranging from materials science, microelectronics, phononics, microfluidics to biomedicine requiring millimeter to centimeter-sized objects embedding micrometric features. In the recent years, several technologies have been employed to provide optimal features in terms of object size flexibility, printing resolution, large materials library and fabrication speed. In this work, we report a fully customizable single-photon absorption 3D fabrication methodology based on direct laser fabrication. To validate this approach and highlight the versatility of the setup, we have fabricated a comprehensive ensemble of 2D and 3D designs with potential applications in biomimetics, 3D scaffolding and microfluidics. The high degree of tunability of the reported fabrication system allows tailoring the laser power, slicing and fabrication speed for each single area of the design. These unique features enable a rapid prototyping of millimeter to centimeter-sized objects involving 3D architectures with true freestanding subunits and micrometric feature reproducibility. The presented strategy fills indeed the current technological gap related to the development of meso-scale architectures required in multidisciplinary fields of research.

144617
18230
05/07/2018

Première démonstration expérimentale d’un interrupteur HEMT normally-off en GaN avec une région P-GaN enterrée

A.CHAPELLE, E.FRAYSSINET, Y.CORDIER, Y.SPIEGEL, L.B.BENMOSTEFA, D.TREMOUILLES, K.ISOIRD, F.MORANCHO, J.TASSELLI, P.AUSTIN, D.HACHEM, C.HALOUI

MICA, CRHEA, Ion Beam Services, ISGE, LCIP2, CEA TECH

Manifestation avec acte : Symposium de Génie Electrique ( SGE ) 2018 du 03 juillet au 05 juillet 2018, Nancy (France), Juillet 2018, 6p. , N° 18230

Lien : https://hal.laas.fr/hal-01848210

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Abstract

Un nouveau concept d'interrupteur de puissance HEMT en GaN présentant la fonctionnalité « normally-off » est expérimentalement validé. L'introduction d'une couche P-GaN suffisamment dopée (autour de 2 x 10 18 cm-3) au sein de la couche buffer GaN NID, en-dessous de l'électrode de grille et sous l'interface AlGaN / GaN, permet d'obtenir une tension de seuil positive de 0,8 V, soit un décalage significatif supérieur à 6 V par rapport à celle d'un HEMT conventionnel « normally-on ».

144283
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