Retour au site du LAAS-CNRS

Laboratoire d’analyse et d’architecture des systèmes

Publications de l'équipe MPN

Choisir la langue : FR | EN

217documents trouvés

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, Vol.310, Novembre 2018, Chapter 12, pp.283-2 , N° 18228

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

Diffusable

Plus d'informations

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

Diffusable

Plus d'informations

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

Diffusable

Plus d'informations

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
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

Diffusable

Plus d'informations

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

Diffusable

Plus d'informations

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
18380
01/07/2018

A differential Hall effect measurement method with sub-nanometre resolution for active dopant concentration profiling in ultrathin doped Si 1− x Ge x and Si layers

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

MPN, ST Microelectronics, CEA-LETI

Revue Scientifique : Beilstein Journal of Nanotechnology, Vol.9, pp.1926-1939, Juillet 2018 , N° 18380

Lien : https://hal.archives-ouvertes.fr/hal-01921179

Diffusable

Plus d'informations

Abstract

In this paper, we present an enhanced differential Hall effect measurement method (DHE) for ultrathin Si and SiGe layers for the investigation of dopant activation in the surface region with sub-nanometre resolution. In the case of SiGe, which constitutes the most challenging process, we show the reliability of the SC1 chemical solution (NH 4 OH/H 2 O 2 /H 2 O) with its slow etch rate, stoi-chiometry 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 annealing) in two material systems: 6 nm thick SiGeOI and 11 nm thick SOI. In both cases, DHE is shown to be a uniquely sensitive characterisation technique for a detailed investigation of dopant activation in ultra-shallow layers, providing sub-nanometre resolution for both dopant concentration and carrier mobility depth profiles

145275
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

Diffusable

Plus d'informations

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

Diffusable

Plus d'informations

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
18329
01/05/2018

Three-dimensional vertical Si nanowire MOS capacitor model structure for the study of electrical versus geometrical Si nanowire characteristics

E.HOURDAKIS, A.CASANOVA, G.LARRIEU, A.G.NASSIOPOULOU

NCSR Democritos, MPN

Revue Scientifique : Solid State Electronics, Vol.143, pp.77-82, Mai 2018 , N° 18329

Lien : https://hal.archives-ouvertes.fr/hal-01898402

Diffusable

Plus d'informations

Abstract

Three-dimensional (3D) Si surface nanostructuring is interesting towards increasing the capacitance density of a metal-oxidesemiconductor (MOS) capacitor, while keeping reduced footprint for miniaturization. Si nanowires (SiNWs) can be used in this respect. With the aim of understanding the electrical versus geometrical characteristics of such capacitors, we fabricated and studied a MOS capacitor with highly ordered arrays of vertical Si nanowires of different lengths and thermal silicon oxide dielectric, in comparison to similar flat MOS capacitors. The high homogeneity and ordering of the SiNWs allowed the determination of the single SiNW capacitance and intrinsic series resistance, as well as other electrical characteristics (density of interface states, flat-band voltage and leakage current) in relation to the geometrical characteristics of the SiNWs. The SiNW capacitors demonstrated increased capacitance density compared to the flat case, while maintaining a cutoff frequency above 1 MHz, much higher than in other reports in the literature. Finally, our model system has been shown to constitute an excellent platform for the study of SiNW capacitors with either grown or deposited dielectrics, as for example high-k dielectrics for further increasing the capacitance density. This will be the subject of future work.

144939
18364
01/04/2018

Split-Channel Ballistic Transport in an InSb Nanowire

J.C.ESTRADA SALDANA, Y.M.NIQUET, J.P.CLEUZIOU, E.LEE, D.CAR, S.PLISSARD, E.P.A.M.BAKKERS, S.DE FRANCESCHI

CEA Grenoble, Univ. de Grenoble, Eindhoven, MPN

Revue Scientifique : Nano Letters, Vol.18, N°4, pp.2282-2287, Avril 2018 , N° 18364

Lien : https://hal.laas.fr/hal-01921932

Diffusable

Plus d'informations

Abstract

We report an experimental study of one-dimensional (1D) electronic transport in an InSb semiconducting nanowire. A total of three bottom gates are used to locally deplete the nanowire, creating a ballistic quantum point contact with only a few conducting channels. In a magnetic field, the Zeeman splitting of the corresponding 1D sub-bands is revealed by the emergence of conductance plateaus at multiples of e2/h, yet we find a quantized conductance pattern largely dependent on the configuration of voltages applied to the bottom gates. In particular, we can make the first plateau disappear, leaving a first conductance step of 2e2/h, which is indicative of a remarkable 2-fold sub-band degeneracy that can persist up to several tesla. For certain gate voltage settings, we also observe the presence of discrete resonant states producing conductance features that can resemble those expected from the opening of a helical gap in the sub-band structure. We explain our experimental findings through the formation of two spatially separated 1D conduction channels.

145139
Les informations recueillies font l’objet d’un traitement informatique destiné à des statistiques d'utilisation du formulaire de recherche dans la base de données des publications scientifiques. Les destinataires des données sont : le service de documentation du LAAS.Conformément à la loi « informatique et libertés » du 6 janvier 1978 modifiée en 2004, vous bénéficiez d’un droit d’accès et de rectification aux informations qui vous concernent, que vous pouvez exercer en vous adressant à
Pour recevoir une copie des documents, contacter doc@laas.fr en mentionnant le n° de rapport LAAS et votre adresse postale. Signalez tout problème de dysfonctionnement à sysadmin@laas.fr. http://www.laas.fr/pulman/pulman-isens/web/app.php/