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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
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.

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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
18275
01/07/2018

Revisiting the Vibrational and Optical Properties of P3HT: A Combined Experimental and Theoretical Study

L.FAROUIL, F.ALARY, E.BEDEL-PEREIRA, J.L.HEULLY

MPN, LCPQ-IRSAMC

Revue Scientifique : Journal of Physical Chemistry A, Vol.122, N°32, pp.6532-6545, Juillet 2018 , N° 18275

Lien : https://hal.archives-ouvertes.fr/hal-01873591

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Abstract

We demonstrate that DFT-based calculations can provide straightforward means to analyze the effect of aggregation on the optical properties of regioregular P3HT oligomers of different lengths (up to 20-mers) and of bioligomers of 8-mers in two different conformations. Our conclusions substantially differ from those obtained previously by applying the exciton model. Indeed, analysis of Huang–Rhys factors has evidenced that two vibrational modes, a collective mode and an effective mode, are combined in the vibronic structure of the absorption spectrum of oligothiophene. Computed spectra match perfectly their experimental counterparts provided we consider that the oligomer and at least the five lowest excited states of bioligomers behave as absorbers, and that both oligomer and bioligomer contribute to the emission spectra. Study of the nature of the Franck–Condon excitation and optimization of the five lowest excited singlet states indicate that high (hot) excited states of the bioligomer may play an important role in the initiation of charge separation and highlight the importance to take into account the relaxation processes in the theoretical modeling of emission properties.

144592
18168
05/06/2018

Self-Aligned Functionalization Approach to Order Neuronal Networks at the Single-Cell Level

A.CASANOVA, MC.BLATCHE, C.FERRE, H.MARTIN, D.GONZALES DUNIA, L.NICU, G.LARRIEU

MPN, I2C, INSERM, MEMS

Revue Scientifique : Langmuir, Vol.34, N°22, pp.6612-6620, Juin 2018 , N° 18168

Lien : https://hal.laas.fr/hal-01816434

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Abstract

Despite significant progress, our knowledge of the functioning of the central nervous system still remains scarce to date. A better understanding of its behavior, in either normal or diseased conditions, goes through an increased knowledge of basic mechanisms involved in neuronal function, including at the single-cell level. This has motivated significant efforts for the development of miniaturized sensing devices to monitor neuronal activity with high spatial and signal resolution. One of the main challenges remaining to be addressed in this domain is, however, the ability to create in vitro spatially ordered neuronal networks at low density with a precise control of the cell location to ensure proper monitoring of the activity of a defined set of neurons. Here, we present a novel self-aligned chemical functionalization method, based on a repellant surface with patterned attractive areas, which permits the elaboration of low-density neuronal network down to individual cells with a high control of the soma location and axonal growth. This approach is compatible with complementary metal-oxide–semiconductor line technology at a wafer scale and allows performing the cell culture on packaged chip outside microelectronics facilities. Rat cortical neurons were cultured on such patterned surfaces for over one month and displayed a very high degree of organization in large networks. Indeed, more than 90% of the network nodes were settled by a soma and 100% of the connecting lines were occupied by a neurite, with a very good selectivity (low parasitic cell connections). After optimization, networks composed of 75% of unicellular nodes were obtained, together with a control at the micron scale of the location of the somas. Finally, we demonstrated that the dendritic neuronal growth was guided by the surface functionalization, even when micrometer scale topologies were encountered and we succeeded to control the extension growth along one-dimensional-aligned nanostructures with sub-micrometrical scale precision. This novel approach now opens the way for precise monitoring of neuronal network activity at the single-cell level.

143896
18129
28/05/2018

Nanoscale measurements of phosphorous-induced lattice expansion in nanosecond laser annealed germanium

S.BONINELLI, R.MILAZZO, R.CARLES, F.HOUDELLIER, R.DUFFY, K.HUET, A.LA MAGNA, E.NAPOLITANI, F.CRISTIANO

CNR-IMM, Catania, University of Padova, CEMES/CNRS, Tyndall, SCREEN-LASSE, MPN

Revue Scientifique : APL Materials, Vol.6, N°5, 058504p., Mai 2018 , N° 18129

Lien : https://hal.archives-ouvertes.fr/hal-01796115

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Abstract

Laser Thermal Annealing (LTA) at various energy densities was used to recrystallize and activate amorphized germanium doped with phosphorous by ion implantation. The structural modifications induced during the recrystallization and the related dopant diffusion were first investigated. After LTA at low energy densities, the P electrical activation was poor while the dopant distribution was mainly localized in the poly- crystalline Ge resulting from the anneal. Conversely, full dopant activation (up to 1 × 10 20 cm 3 ) in a perfectly recrystallized material was observed after annealing at higher energy densities. Measurements of lattice parameters performed on the fully activated structures show that P doping results in a lattice expansion, with a perpen- dicular lattice strain per atom β Ps = +0.7 ± 0.1 Å 3 . This clearly indicates that, despite the small atomic radius of P compared to Ge, the “electronic contribution” to the lattice parameter modification (due to the increased hydrostatic deformation potential in the conduction band of P doped Ge) is larger than the “size mismatch contribu- tion” associated with the atomic radii. Such behavior, predicted by theory, is observed experimentally for the first time, thanks to the high sensitivity of the measurement techniques used in this work

143594
18066
01/04/2018

Computational fluid dynamics simulation of the ALD of alumina from TMA and H2O in a commercial reactor

G.P.GAKIS, H.VERGNES, E.SCHEID, C.VAHLAS, B.CAUSSAT, A.BOUDOUVIS

LGC, MPN, CIRIMAT, NTUA

Revue Scientifique : Chemical Engineering Research and Design: Transactions of the Institution of Chemical Engineers Part A, Vol.132, pp.795-811, Avril 2018 , N° 18066

Lien : https://hal.archives-ouvertes.fr/hal-01730196

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Abstract

A three-dimensional Computational Fluid Dynamics model is built for a commercial Atomic Layer Deposition (ALD) reactor, designed to treat large area 20 cm substrates. The model aims to investigate the effect of the reactor geometry and process parameters on the gas flow and temperature fields, and on the species distribution on the heated substrate surface, for the deposition of Al2O3 films from trimethyl aluminum and H2O. The investigation is performed in transient conditions, without considering any surface reaction. A second CFD model is developed for the feeding system of the reactor, in order to calculate the unknown reactant inlet flow rates. The two models are coupled via a computational strategy dictated by the available experimental measurements. Results show that a purging flow entering the reactor through its loading door affects the flow field above the substrate surface and causes non-uniformity in the temperature and reactants concentration on the substrate surface. During the TMA pulse, a recirculation sets in above the substrate surface, leading to a non-uniform distribution of species on the surface.

142837
18073
21/03/2018

Dopant Activation in Ultra-thin SiGeOI and SOI layers characterised by Differential Hall Effect

R.DAUBRIAC, E.SCHEID, S.JOBLOT, R.BENEYTON, P.ACOSTA ALBA, S.KERDILES, F.CRISTIANO

MPN, ST Microelectronics, CEA-LETI

Manifestation avec acte : Joint International EUROSOI Workshop and International Conference on Ultimate Integration on Silicon ( EUROSOI-ULIS ) 2018 du 19 mars au 21 mars 2018, Grenade (Espagne), Mars 2018, 2p. , N° 18073

Lien : https://hal.laas.fr/hal-01735436

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Abstract

The reduction of the contact resistance RC is one of the most challenging issues related to the miniaturisation of advanced MOSFET architectures, including FDSOI technology (Fully Depleted Silicon-On-Insulator). RC strongly depends on the active dopant concentration at the semiconductor/salicide interface. It is therefore essential that electrical activation at different depths within a doped layer is reliably determined to optimise the fabrication processes. In this paper, we firstly present a Differential Hall Effect (DHE) method which allows measuring the active dopant concentration profile close to the surface with nm resolution for ultra-shallow doped Si1-xGex and Si layers. Then, we present DHE measurements made on junctions processed with advanced techniques, including nsec LTA and msec DSA anneals.

142935
18068
14/03/2018

A Differential Hall Effect method with sub-nanometre resolution for active dopant concentration profiling in ultra-thin Si 1-x Ge x and Si doped layers

R.DAUBRIAC, E.SCHEID, S.JOBLOT, R.BENEYTON, P.ACOSTA ALBA, S.KERDILES, F.CRISTIANO

MPN, ST Microelectronics, CEA-LETI

Rapport LAAS N°18068, Mars 2018, 34p.

Lien : https://hal.laas.fr/hal-01730674

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In this paper, we present an enhanced Differential Hall Effect method (DHE) for Si and SiGe ultrathin layers for the investigation of dopant activation in the surface region with sub-nanometre resolution. In the case of SiGe case, which constitutes the most challenging process, we show the reliability of the SC1 chemical solution (NH4OH:H2O2:H2O) thanks to its slow etch rate, stoichiometry conservation and low roughness generation. The reliability of a complete DHE procedure, with an etching step as small as 0.5 nm, is demonstrated on a dedicated 20 nm-thick SiGe test structure fabricated by CVD and uniformly doped in situ during growth. The developed method is finally applied to the investigation of dopant activation achieved by advanced annealing methods (including millisecond and nanosecond laser anneal) in two material systems: 6 nm-thick SiGeOI and 11 nm-thick SOI. In both cases, DHE is shown to be a unique sensitive characterisation technique for a detailed investigation of dopant activation in ultra-shallow layers, providing sub-nm resolution for both dopant concentration and carrier mobility depth profiles.

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