Transport d’Energie aux Petites Echelles

 

Présentation

Cette thématique émarge à deux enjeux sociétaux majeurs : le défit de l’information et le défit énergétique. Dans les deux cas cela consiste à trouver les matériaux idéaux pour transporter l’information toujours plus vite et à rendre viables de nouvelles sources d’énergie.

Une approche chimique consiste à synthétiser les matériaux et à les caractériser. Dans cette approche certaines barrières restent infranchissables – il n’existe pas d’isolants thermiques conducteurs électrique –
Une approche alternative dite « physique » vise à controller les propriétés de transport de la matière en la structurant à l’échelle nanométrique. Il est alors possible de passer outre les barrières. Il devient alors possible de réaliser des matériaux isolants thermiques qui conduisent l’électricité (les matériaux de demain pour la thermoélectricité), de réaliser des isolant électriques qui pourront évacuer la chaleur produite par les microprocesseurs (ainsi décupler la puissance calcul des ordinateurs), guider et focaliser la lumière à l’échelle du nanomètre dans des guides d’onde plasmonique.

Dès le début la production des ces nouveaux matériaux à rencontré un verrou majeur… : une absence totale de méthodes de caractérisation. En effet, les petites échelles spatiales impliquent des échelles de temps très courtes, les porteurs d’énergie parcourant des distances nano métriques en quelques femto secondes.

Nous développons des techniques basées sur l’utilisation de microscopes à force atomique et de lasers implusionnels femtosecondes pour caractériser aussi bien des matériaux que des composants ou des micro-systèmes.

Notre expertise permet de développer des techniques très avancées (à l’état de l’art) de caractérisations de nano matériaux. Ainsi à titre d’exemple nous pouvons -filmer le passage d’une onde de chaleur à la vitesse de la lumière, -étudier le comportement d’un plasmon focalisé dans un point chaud nanométrique, -automatiser la mesure de propriétés de transport dans les bibliothèques de nano matériaux, -faire de l’échographie à l’échelle cellulaire.

Tout ce savoir-faire est transferable… le projet Element Metrology a donné naissance à une spin-off de l’Université née en décembre 2016 NETA, engendrée par le LOMA et l’I2M. NETA a pour vocation à proposer des solutions clefs en main pour la caractérisation et l’imagerie de nano matériaux.

L’équipe printemps 2014

La thématique est composée des membres suivants :

Anciens membres de la thématique :

  • Martin Berthel, Post Doc
  • Allaoua Abbas, Ingénieur maturation
  • Quentin D’Acremont, PhD
  • Alexis Casanova, PhD
  • Olga Lozan, PhD
  • Ioannis Petsagkourakis, PhD
  • Bryan Kuropatwa, Post Doc
  • Gilles Pernot, PhD
  • Hatim Baida, Post Doc
  • Arnaud Royon, Post Doc
  • Jonah Shaver, Post Doc
  • Julien Chandezon, PhD
  • Gaetan Calbris, PhD
  • Etienne Puyoo, PhD
  • Lilian Courjaud, PhD
  • LN Michel, PhD
  • Amine Sahli, PhD
  • Younes Ezzahri, PhD
  • Imad Abbadi, PhD
  • Luis-David Patno-Lopez, PhD
Tips & Photons

Femtosecond Pump-Probe & AFM based Thermal Imaging

Tips & Photons

Thèmes de recherche

Le groupe étudie l’interaction entre la lumière, la chaleur et l’électricité dans les nano-matériaux et les micro-systèmes. Nous développons des techniques d’imagerie innovantes utilisant des pointes de champ proche associées (ou non) à des lasers femtoseconde.

Du transfert de Technologie à la Physique Fondamentale…

Le savoir-faire du groupe consiste à développer des nouvelles techniques d’imagerie aux nano-échelles avec des résolutions temporelles femtoseconde (à titre d’exemple : là où il faudrait d’ordinaire 40 heures pour obtenir un signal en un point unique, 10 minutes suffisent pour enregistrer un film du passage d’une onde de chaleur à la vitesse de la lumière à la cadence de 40 Téra images à la seconde).

Cette nouvelle technique associée à de l’imagerie de champ proche permet de revisiter des domaines de la physique fondamentale :

  • Nano Phononique (LOMA-I2M) : Nanothermie, Acoustique picoseconde, SThM, Identification de propriétés thermiques de nano-matériaux (nano-fils, super-réseaux, couches minces).
  • Nano Plasmonique (LOMA-LP2N) : Imagerie avancée via les plasmons de surface, confinement de la lumière pour dépasser la limite de diffraction optique.
  • Imagerie Thermique Optique et de Champ Proche (LOMA-IMS) : Analyse de défaillance de composants opto-électroniques pour les applications spatiales.
  • Transfert de Technologie (LOMA-Amplitude Systèmes) : Développement de nouvelles techniques d’imagerie ultra-rapide à base d’échantillonnage optique hétérodyne.

Résultats

Voici quelques résultats sur les thématiques sur lesquelles le groupe travaille actuellement

Thermo plasmonique
Il s’agit d’étudier le transport des plasmons au travers des electrons chauds produits par les plasmon quand on les focalise sous la limite de diffraction. Il apparait un ralentissement non attendu de la dynamique électronique. Ce ralentissement pourrait être mis à profit dans un nouvelle génération cellules photo-voltaïques.

– Increased rise time of electron temperature during adiabatic plasmon focusing, Nature Communications, 8 (1), art. no. 1656, . (2017)
–  Anomalous Light Absorption around Subwavelength Apertures in Metal Films, Phys. Rev. Lett. 112, 193903 (2014)


Nano thermique
Les techniques d’échantillonnage optique hétérodyne (brevetées) associées à la thermoreflectance résolue en temps permettent de caractériser thermiquement en routine des souches minces (50nm), des super-réseaux, des nanofils, des nanoparticules. Nous avons pu mettre en evidence un forte reduction (2 ordres de grandeurs) de la conductivité thermique pour du silicium nano structuré.
D’autre part nous avons pu mettre en evidence les effets de la nanostrucuturation sur des nanofils individuels par microscopie thermique de champ proche (SThM).

– G. Pernot, M. Stoffel, I. Savic, A. Jacquot, J. Schumann, G. Savelli, A. Rastelli, O.G. Schmidt, J. M. Rampnoux, S. Dilhaire, M. Plissonnier, S. Wang, and N. Mingo, “Precise control of thermal conductivity at the nanoscale via individual phonon barriers”, Nature Materials, Volume : 9, Pages : 491–495 (2010
– Rojo, M.M., Martín, J., Grauby, S., Borca-Tasciuc, T., Dilhaire, S., Martin-Gonzalez, M. Decrease in thermal conductivity in polymeric P3HT nanowires by size-reduction induced by crystal orientation: New approaches towards thermal transport engineering of organic materials (2014) Nanoscale, 6 (14), pp. 7858-7865


Nanostructuration à grande échelle
Avec le groupe du Georges Hadziioannou (LCO Bdx) nous avons pu nano structurer des polymères par inscription optique. Nous avons montrer que nous pouvions propager un ordre de période nanométrique sur des distances millimétriques. La prochaine étape sera de greffer des nanoparticules dont l’inter-distance sera assurée par le polymère pour contrôler les propriétés de transport en modulant les propriétés plasmoniques.

– Karim Aissou, Jonah Shaver, Guillaume Fleury, Gilles Pécastaings, Cyril Brochon, Christophe Navarro, Stéphane Grauby, Jean-Michel Rampnoux, Stefan Dilhaire and Georges Hadziioannou, Nanoscale Block Copolymer Ordering Induced by Visible Interferometric Micropatterning: A Route towards Large Scale Block Copolymer 2D Crystals, Adv. Mater. 25, 213–217 (2013)


Imagerie acoustique cellulaire
Le potentiel de nos techniques en matière d’imagerie cellulaire est immense. Nous avons pu échographier des cellules biologiques. Ce travail a servi de tremplin pour le développement de la société NETA issue du groupe qui a vu le jour en 2017 à l’issue de sa maturation.

– Dehoux, T., Ghanem, M.A., Zouani, O.F., Rampnoux, J.-M., Guillet, Y., Dilhaire, S., Durrieu, M.-C., Audoin, B. All-optical broadband ultrasonography of single cells (2015) Scientific Reports, 5, art. no. 8650

Publications

Brevets

– Surface preparation method
Publication number: 20150140267
Abstract: The invention relates to a process for the preparation, by spatial distribution of light intensity, of a surface in relief promoting order and spatial coherence serving as a guide for the organization, on nano- and micrometre scales, of an overlayer on the surface in particular of block copolymers.

– Optical Heterodyne Sampling Device
Publication number: 20080251740
Abstract: An optical heterodyne sampling device includes: two pulsed laser sources which may have a jitter and which can receive respectively a pump beam and a probe beam having respective repetition frequencies Fs and Fp; and an element for combining the pump beam and the probe beam which are intended to be passed over a sample, consisting of a signal channel including a system for the photodetection of the response signal from the sample and a system for acquiring the photodetected signal, which is connected to the signal channel. According to the invention, Fs and Fp are essentially constant and the acquisition system includes an acquisition trigger element. A synchronization channel is connected to the trigger element, and includes a device for measuring the beat frequency |Fs-Fp| which can generate a synchronization signal comprising pulses each time the pulses of the pump beam and the probe beam coincide.


 Publications depuis 2010

  1. Petsagkourakis, I., Pavlopoulou, E., Cloutet, E., Chen, Y.F., Liu, X., Fahlman, M., Berggren, M., Crispin, X., Dilhaire, S., Fleury, G., Hadziioannou, G, Correlating the Seebeck coefficient of thermoelectric polymer thin films to their charge transport mechanism, Organic Electronics: physics, materials, applications, 52, pp. 335-341, (2018). (IF 3,5)
  2. Lozan, O., Sundararaman, R., Ea-Kim, B., Rampnoux, J.-M., Narang, P., Dilhaire, S., Lalanne, P., Increased rise time of electron temperature during adiabatic plasmon focusing, Nature Communications, 8 (1), art. no. 1656, . (2017) (IF 13)
  3. Coffy, E., Dodane, G., Euphrasie, S., Mosset, A., Vairac, P., Martin, N., Baida, H., Rampnoux, J.M., Dilhaire, S., Anisotropic propagation imaging of elastic waves in oriented columnar thin films,  Journal of Physics D: Applied Physics, 50 (48), art. no. 484005, . (2017) (IF 2,6)
  4. D’Acremont, Q., Pernot, G., Rampnoux, J.-M., Furlan, A., Lacroix, D., Ludwig, A., Dilhaire, S., High-throughput heterodyne thermoreflectance: Application to thermal conductivity measurements of a Fe-Si-Ge thin film alloy library, Review of Scientific Instruments, 88 (7), art. no. 074902, (2017) (IF 1,5)
  5. Furlan, A., Grochla, D., D’Acremont, Q., Pernot, G., Dilhaire, S., Ludwig, A., Influence of Substrate Temperature and Film Thickness on Thermal, Electrical, and Structural Properties of HPPMS and DC Magnetron Sputtered Ge Thin Films, Advanced Engineering Materials, 19 (5), art. no. 1600854, .(2017) (IF 2,3)
  6. Petsagkourakis, I., Pavlopoulou, E., Portale, G., Kuropatwa, B.A., Dilhaire, S., Fleury, G., Hadziioannou, G., Structurally-driven enhancement of thermoelectric properties within poly(3,4-ethylenedioxythiophene) thin films, Scientific Reports, 6, art. no. 30501, (2016) (IF 5,8)
  7. Michaud, J., Béchou, L., Veyrié, D., Laruelle, F., Dilhaire, S., Grauby, S., Thermal Behavior of High Power GaAs-Based Laser Diodes in Vacuum Environment, IEEE Photonics Technology Letters, 28 (6), art. no. 7347350, pp. 665-668. (2016)
  8. Casanova, A., D’Acremont, Q., Santarelli, G., Dilhaire, S., Courjaud, A., Ultrafast amplifier additive timing jitter characterization and contro, lOptics Letters, 41 (5), pp. 898-900. (2016)
  9. Chandezon, J., Rampnoux, J.-M., Dilhaire, S., Audoin, B., Guillet, Y. In-line femtosecond common-path interferometer in reflection mode (2015) Optics Express, 23 (21), pp. 27011-27019 (IF 3,5)
  10. Savelli, G., Silveira Stein, S., Bernard-Granger, G., Faucherand, P., Montés, L., Dilhaire, S., Pernot, G. Titanium-based silicide quantum dot superlattices for thermoelectrics applications (2015) Nanotechnology, 26 (27), art. no. 275605 (IF 4)
  11. Dehoux, T., Ghanem, M.A., Zouani, O.F., Rampnoux, J.-M., Guillet, Y., Dilhaire, S., Durrieu, M.-C., Audoin, B. All-optical broadband ultrasonography of single cells (2015) Scientific Reports, 5, art. no. 8650 (IF 5,8)
  12. Rojo, M.M., Martín, J., Grauby, S., Borca-Tasciuc, T., Dilhaire, S., Martin-Gonzalez, M. Decrease in thermal conductivity in polymeric P3HT nanowires by size-reduction induced by crystal orientation: New approaches towards thermal transport engineering of organic materials (2014) Nanoscale, 6 (14), pp. 7858-7865 (IF 6).
  13. O. Lozan, M. Perrin, B. Ea-Kim, J. M. Rampnoux, S. Dilhaire, and P. Lalanne, Anomalous Light Absorption around Subwavelength Apertures in Metal Films, Phys. Rev. Lett. 112, 193903 (2014) (IF 8)
  14. A. Abbas, Y. Guillet, J.-M. Rampnoux, P. Rigail, E. Mottay, B. Audoin, and S. Dilhaire, Picosecond time resolved opto-acoustic imaging with 48 MHz frequency resolution, Optics Express, Vol. 22, Issue 7, pp. 7831-7843 (2014) (IF 3,8)
  15. M. Muñoz Rojo, S. Grauby, J.-M. Rampnoux, O. Caballero-Calero, M. Martin-Gonzalez and S. Dilhaire, Fabrication of Bi2Te3 nanowire arrays and thermal conductivity measurement by 3ω-scanning thermal microscopy, J. Appl. Phys. 113, 054308 (2013) (IF 2,3)
  16. Karim Aissou, Jonah Shaver, Guillaume Fleury, Gilles Pécastaings, Cyril Brochon, Christophe Navarro, Stéphane Grauby, Jean-Michel Rampnoux, Stefan Dilhaire and Georges Hadziioannou, Nanoscale Block Copolymer Ordering Induced by Visible Interferometric Micropatterning: A Route towards Large Scale Block Copolymer 2D Crystals, Adv. Mater. 25, 213–217 (2013) (IF 14,8)
  17. S. Dilhaire, G. Pernot, G. Calbris, J. M. Rampnoux, and S. Grauby, Heterodyne picosecond thermoreflectance applied to nanoscale thermal metrology, J. Appl. Phys. 110, 114314 (2011) (IF 2,3)
  18. Altet, J., Mateo, D., Perpiñà, X., Grauby, S., Dilhaire, S., Jordà, X., Nonlinearity characterization of temperature sensing systems for integrated circuit testing by intermodulation products monitoring, Review of Scientific Instruments 82 (9) , art. no. 094902, 2011 (IF 1,8)
  19. Pradere, C., Clerjaud, L., Batsale, J.C., Dilhaire, S., High speed heterodyne infrared thermography applied to thermal diffusivity identification, Review of Scientific Instruments 82 (5) , art. no. 054901, 2011 (IF 1,8)
  20. Etienne Puyoo, Stéphane Grauby, Jean-Michel Rampnoux, Emmanuelle Rouvière, and Stefan Dilhaire,  Scanning thermal microscopy of individual silicon nanowires, J. Appl. Phys. 109, 024302 (2011) (IF 2,3)
  21. Thermal exchange radius measurement: Application to nanowire thermal imaging, Puyoo, E., Grauby, S., Rampnoux, J.-M., Rouviere, E., Dilhaire, S. , Review of Scientific Instruments 81 (7), art. no. 073701  (2010) (IF 1,8)
  22. Aldrete-Vidrio, E., Mateo, D., Altet, J., Salhi, M. A., Grauby, S., Dilhaire, S . Strategies for built-in characterization testing and performance monitoring of analog RF circuits with temperature measurements. Measurement Science and Technology, 21(7)  (2010) (IF 1,5)
  23. Heterodyne method with an infrared camera for the thermal diffusivity estimation with periodic local heating in a large range of frequencies (25 Hz to upper than 1 kHz), Lilian Clerjaud, Christophe Pradere, Jean-Christophe Batsale and Stefan Dilhaire, Quantitative InfraRed Thermography Journal Volume 7, Issue 1, 2010 (IF 1,2)
  24. G. Pernot, M. Stoffel, I. Savic, A. Jacquot, J. Schumann, G. Savelli, A. Rastelli, O.G. Schmidt, J. M. Rampnoux, S. Dilhaire, M. Plissonnier, S. Wang, and N. Mingo, “Precise control of thermal conductivity at the nanoscale via individual phonon barriers”, Nature Materials, Volume : 9, Pages : 491–495 (2010) (IF 35,7)

Conférences Invitées depuis 2010

  1. Invited lecture Hamamatsu Technology Days 2017, One trillion images per second applied to Nanoplasmonics, Nanophononics, Ultrasonic 22/11/2017
  2. Invited lecture at SP15 at META’16 7th International Conference on Metamaterials, Photonic Crystals and Plasmonics 2016, Malaga Spain.
  3. Filming and Imaging Ultra-Fast Energy Transfer in Pump-Probe Experiments, Fall MRS Meeting in Dec. 2013, in Boston MA
  4. Phonons in nanomaterials – theory, experiments, and applications, in the Fall MRS Meeting in Dec. 2011, in Boston MA.
  5. Thermal Properties Characterization of Advanced Materials for Nanoelectronics, International Conference on Frontiers of Characterization and Metrology for Nanoelectronics 2011, MINATEC France.
  6. Thermal Properties Characterization of Thermoelctric Nanomaterials, European Workshop on Electrochemical Deposition of Thermoelectric Materials,2011, Germany.
  7. Nanoscale Thermal Metrology : Application to Thermoelectrics, 1st workshop on thermoelctric, TOTAL, La Défense Feb 2011 France.
  8. When Photons Listen To Phonons, BIO-NANO-ROBO Seminar Series, July 27th 2010, LIMMS Tokyo, Japan.
  9. Femtosecond Studies of Superlattices: Phonon Spectroscopy and Nanothermal Metrology, ICREA workshop on phonon engineering , 2010, Sant Feliu de Guixols, Spain

Conférences depuis 2010

  1. Martin Berthel, Olga Lozan, Buntha Ea Kim, Philippe Lalanne, Stefan Dilhaire, Ultrafast Interferometric Measurement of Plasmonic Field in a Hot Spot by Thermoreflectance, NM2: Nanoscale Heat Transport—From Fundamentals to Devices, 2017 MRS Spring Meeting Symposium
  2. Stefan Dilhaire, Olga Lozan, Buntha Ea Kim, Philippe Lalanne Ultrafast Hot Carrier Imaging in a Plasmonic Taper, Nanoscale and Microscale Heat Transfer V, Eurotherm Seminar No 108, 2016
  3. A. Casanova, Q. D’Acremont, G. Santarelli, S. Dilhaire, and A. Courjaud, « Sub-10fs jitter compensation system for femtosecond amplifiers for accelerators, » in 2015 European Conference on Lasers and Electro-Optics – European Quantum Electronics Conference,  (Optical Society of America, 2015), paper CF_6_4. 
  4. O. Lozan, B. Ea-Kim, M. Perrin, S. Dilhaire, and P. Lalanne, Hot-Electron Production in Plasmonic Devices, 7th International Conference on Surface Plasmon Photonics (SPP7) 2015
  5. Dodane, G., Euphrasie, S., Teyssieux, D., Salman, S., Vairac, P., Baida, H., Rampnoux, J.M., Dilhaire, S., Bertin, F., Chabli, A., Rigail, P., Femtosecond heterodyne pump probe platform, (2015) 2014 European Frequency and Time Forum, EFTF 2014, art. no. 7331431, pp. 79-82. 
  6. Altet, J., Aldrete-Vidrio, E., Reverter, F., Gómez, D., González, J.L., Onabajo, M., Silva-Martinez, J., Martineau, B., Perpiña, X., Abdallah, L., Stratigopoulos, H., Aragonés, X., Jordà, X., Vellvehi, M., Dilhaire, S., Mir, S., Mateo, D., »Review of temperature sensors as monitors for RF-MMW built-in testing and self-calibration schemes, 2014, »Midwest Symposium on Circuits and Systems »
  7. Abbas, A., Guillet, Y., Rampnoux, J.-M., Carlier, J., Rigail, P., Mottay, E., Audoin, B., Dilhaire, S., »Asynchronous ultrafast pump-probe experiments: Towards high speed ultrafast imaging with ultrahigh spectral resolution »,2013, »Optics InfoBase Conference Papers »
  8. Abbas, A., Guillet, Y., Rampnoux, J.-M., Carlier, J., Rigail, P., Mottay, E., Audoin, B., Dilhaire, S., »Asynchronous ultrafast pump-probe experiments: Towards high speed ultrafast imaging with ultrahigh spectral resolution »,2013, »Optics InfoBase Conference Papers »
  9. Grauby, S., Puyoo, E., Rojo, M.M., Martin-Gonzalez, M., Claeys, W., Dilhaire, S., »Effect of nanostructuration on the thermal conductivity of thermoelectric materials »,2013, »THERMINIC 2013 – 19th International Workshop on Thermal Investigations of ICs and Systems
  10. Abbas, A., Guillet, Y., Rampnoux, J.-M., Curlier, J., Rigail, P., Mottay, E., Audoin, B., Dilhaire, S., »Asynchronous ultrafast pump-probe experiments: Towards high speed ultrafast imaging with ultrahigh spectral resolution »,2013, »2013 Conference on Lasers and Electro-Optics Europe and International Quantum Electronics Conference, CLEO/Europe-IQEC 2013 »
  11. Altet, J., González, J.L., Gomez, D., Perpiñà, X., Grauby, S., Dufis, C., Vellvehi, M., Mateo, D., Dilhaire, S., Jordà, X., »Electro-thermal characterization of a differential temperature sensor and the thermal coupling in a 65nm CMOS IC »,2012, »18th International Workshop on Thermal Investigation of ICs and Systems, THERMINIC 2012 »
  12. Pernot, G., Michel, H., Vermeersch, B., Burke, P., Lu, H., Rampnoux, J.-M., Dilhaire, S., Ezzahri, Y., Gossard, A., Shakouri, A., »Frequency-dependent thermal conductivity in time domain thermoreflectance analysis of thin films »,2011, »Materials Research Society Symposium Proceedings »
  13. Dilhaire S. Phonons in nanomaterials – theory, experiments, and applications, in the Fall MRS Meeting in Dec. 2011, in Boston MA.
  14. Dilhaire S. Thermal Properties Characterization of Advanced Materials for Nanoelectronics, International Conference on Frontiers of Characterization and Metrology for Nanoelectronics, 2011, MINATEC.
  15. Dilhaire S. Thermal Properties Characterization of Thermoelctric Nanomaterials, European Workshop on Electrochemical Deposition of Thermoelectric Materials,
    2011, Germany.
  16. Puyoo, E., Grauby, S., Rampnoux, J.-M., Claeys, W., Rouvière, E., Dilhaire, S. , Simultaneous topographic and thermal imaging of silicon nanowires using a new SThM probe ,16th International Workshop on Thermal Investigations of ICs and Systems, THERMINIC 2010 , art. no. 5636303, pp. 234-239
  17. Michel, H., Pernot, G., Rampnoux, J.-M., Dilhaire, S., Grauby, S., Ezzahri, Y., Shakouri, A., »Investigating coherent zone-folded acoustic phonons in Si/SiGe superlattice by transient thermoreflectance technique »,2010, »Materials Research Society Symposium Proceedings »
  18. Dilhaire, S., Rampnoux, J. -., Grauby, S., Pernot, G., & Calbris, G. (2010). Namoscale thermal transport studied with heterodyne picosecond thermoreflectance. Proceedings of the ASME Micro/Nanoscale Heat and Mass Transfer International Conference 2009, MNHMT  2, pp. 451-456 

 

Offres de Thèses et de Post-Doc

Thesis title Near-field nano Thermometer with femtosecond resolution at nanometer scale (September 2018)
Research project

We propose to combine an atomic force microscope with a pump-probe femtosecond thermoreflectance set-up. This unique technique will offer a femtosecond time resolution associated to a nanometer spatial resolution.

It will be applied to the study of energy transfer inside nanowires (NWs). A pump laser will be focused on the NW surface, creating a temperature increase on top of the NW. The near-field of a probe beam reflected by the NWwill be collected or diffracted (depending on the tip used). Then, the AFM tip will measure the local temperature variation through thermoreflectance.

The NWs are innovating Si or Ge 2H/3C heterostructures which are expected to offer a low thermal conductivity and to be promising materials for thermoelectric applications. The AFM nanothermometer will enable to study the energy transport inside the NWs and analyze the mechanisms responsible for the thermal conductivity reduction with a femtosecond time resolution and a nanometer spatial resolution.

Name of the thesis director(s)

(E-mail, Tel)

Stefan Dilhaire: stefan.dilhaire@u-bordeaux.fr, 05 40 00 27 86

Stéphane Grauby: stephane.grauby@u-bordeaux.fr, 05 40 00 25 09

Group Ultra Fast and NanoScale Energy Transport
List of the partners (lab/company/univ.) C2N, CNRS, Université Paris Sud, Paris-Saclay.

Thesis title Nanoscale Heat Transfer in Non Fourier Materials Studied with Picosecond Time resolved Thermoreflectance (September 2018)
Research project

The main goals of the thesis are to explore and develop a new instrumentation to probe ultra-fast energy transfer in nano structured semiconductors. This ultrafast energy transfer is known as ballistic-diffusive regime, and can be described by the frame of Lévy Walks theory (i.e. super-diffusive regime). Over the past decade, rapid improvement of experimental techniques devoted to “nano” materials characterisation has arisen. For instance, Time-Domain Thermoreflectance (TDTR) and Scanning Thermal Microscopy (SThM) are now well-established techniques to probe energy transport in nano-structured materials. Yet, if those approaches respectively allow spectacular temporal or spatial resolution of heat transfer at nano-scales, they can scarcely describe the ballistic-diffusive regime that exists when length scale and energy carriers mean free path are similar. The latter behaviour is theoretically expected in different semiconductors. It represents a longstanding problem in nanoscale thermal transport for several engineering applications such as heat management, thermal hot spots, thermal boundary resistances, etc. In this framework, the thesis intent to design a new instrumentation to probe super-diffusive phonon transport in nano-materials called Spectral Phonon Super-diffusion Sensor (SPSS). This challenging task shall tackle several scientific issues, especially in the development and the calibration of the SPSS. Among them, there is the handling of a TDTR heterodyne device to work at frequencies up to 10 THz, where thermal wave propagation dominates, keeping low signal to noise ratio. Another critical point is to study artificial Lévy materials mixing alloy and nano- inclusions which will be responsible of super-diffusive behaviour with respect of the modelling pathways. Modelling issues are also possible bottlenecks to the achievement of the project as nanoscale heat transport simulation often imply to use large computational resources and lies on physics which is not fully understood for some crystalline materials and alloys. The latter points are considered in the present project and alternative paths are considered to overcome such issues.

In addition to the development of a new characterisation device and models for nanoscale material thermal properties characterisation, the thesis will aim to deeply investigate innovative nano-materials that will be useful for several technologies like electronics, energy, sensors, etc. Examples of that could be improved cooling of electronic devices, thermoelectric materials with high figure of merit, development of ultrafast magnetic switching materials, etc.

Name of the thesis director(s)

(E-mail, Tel)

Stefan Dilhaire, stefan.dilhaire@u-bordeaux.fr, 05 4000 2786
Group Ultra Fast and NanoScale Energy Transport
List of the partners (lab/company/univ.) For Mobility project: Purdue University, Quantum Engineered Systems & Technology, Laboratory, Birck Nanotechnology Center, USA

LEMTA, Université de Loraine, France