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Functional oxides

Functional oxides present a wide range of key properties (ferroelectricity, pyroelectricity, piezoelectricity, ferromagnetism, multiferroicity, thermoelectricity, superconductivity, ultra-high electro-optic coefficients and strong optical non-linearities, optical transparency combined with electrical conductivity, wide band-gap,…) promising for various advanced applications. Our group studies these materials as thin layers deposited on oxides or semiconductors (Si, Ge, GaAs) substrates by molecular beam epitaxy (MBE), sputtering, sol-gel and atomic layer deposition (ALD), to address applications mainly in the fields of energy harvesting, advanced photonics, plasmonics, and nanoelectronics.

Growth & heterostructures

Oxide MBE, less mature than pulsed laser deposition or sputtering for oxide growth, offers unrivalled flexibility to control the composition and structure at the atomic scale (complex solid solutions, heterostructures, superlattices, doping, interface engineering). Our aim is to exploit this flexibility on the one hand to develop new oxide based nanomaterials having enhanced or novel properties (see Main applications), and on the other hand to integrate by epitaxy functional oxides on semiconductor platforms (Si, Ge, III-V), the main archetypal example being SrTiO3/Si(001) (ANR Lilit, ANR DIAMAWEL) [Saint-Girons CM 2016]. To push oxide MBE beyond its limits, we also propose new concepts for the control of the growth, based on operando measurements of the growth parameters (new concepts for optical flux monitoring, for instance) and of the physical properties of the growing layers and heterostructures (in-situ ellipsometry and curvature measurements, among others).

We are also developing the deposition of functional oxide films on oxide and silicon substrates by sputtering, sol-gel and atomic layer deposition processes. One of the objectives is to demonstrate a chain of value within INL around functional oxides: from material to device.

 

Main applications

  • Energy harvesting:

In the view of thermal energy harvesting, we mainly study pyroelectric and thermoelectric oxides. For pyroelectrics, we have studied pyroelectric energy conversion in PZT layers (regional project, R. Moalla PhD thesis) in collaboration with the INL electronic devices team. In epitaxial layers, we have shown a huge gain of energy conversion with respect to their polycrystalline counterparts [Moalla NE 2017], as well as a large anisotropy of the conversion factor [Moalla SR 2018], strongly impacted by the thermal expansion coefficients mismatch with the substrates [Moalla CrystEngCom 2016]. For thermoelectrics, we have developed n-type La-doped SrTiO3 thermoelectric epitaxial layers with state-of-the-art properties (European H2020 TIPS project, 2014-2018) [Apreutesei STAM 2017]. We have recently developed and studied p-type Sr-doped LaCrO3 thermoelectric epitaxial layers (CSC grant, D. Han PhD thesis, 2017-2020) [Han ACS AEM 2021]. We have also developed the fabrication of an integrated micro thermoelectric module based on these oxides (ANR MITO project, 2018-2021).

 

 

  • Photonics / Plasmonics

In the photonics field, we are developing, in strong interaction with INL i-lum team, tunable and reconfigurable devices exploiting the strong non-linearities characteristic for functional oxides. We have for instance developed new concepts of light modulators integrated on SOI exploiting the strong Pockels effect in ferroelectric BaTiO3 (European FP7 SITOGA project 2013-2017). We are also developing original approaches to engineer the permittivity in oxide superlattice based metamaterials, structured down to the monolayer level. We have for instance demonstrated record near IR hyperbolicity in SrTiO3/(La,Sr)TiO3 superlattices [Bouras ACS Photonics 2019].

The same underlying concept of degenerately doped semiconductor oxides has been used to generate Mid IR plasmons. These have been obtained and tuned over a wide range in Ga or Al doped ZnO nanocrystals and, for the first time, nanowires (coll. ILM and GEMAC, ANR GaZON, 2015-18) [Sallet Cryst Growth & Design 2018].

 

 

Contact: G. Saint-Girons & R. Bachelet

 

Members : A. Apostoluk, R. Bachelet, C. Botella, G. Brémond, B. Canut, A. Danescu, C. Furgeaud,

G. Grenet, A. Lamirand, B. Masenelli, J. Penuelas, P. Regreny, G. Saint-Girons.

Current Docs :

  1. D’Esperonnat (2019-2022) : « Enhanced thermoelectric epitaxial oxide layers »
  2. Sahoo (2021-2024): “Thermotronic: toward autonomous thermal information”

 

Former Docs (last 5 years) :

  1. G. Segantini (2019-2022): “Realization of ferroelectric artificial synapses for hardware implementation of neuromorphic networks”
  2. Han (2017-2020) : “P-type Sr-doped LaCrO3 thermoelectric epitaxial films”
  3. Zhang (2017-2020): “Fabrication, structural and spectroscopic studies of wide bandgap semiconducting nanoparticles of ZnO for application as white light emitting diodes”
  4. Bouras (2016-2019) : ” Ingénierie des propriétés diélectriques d’oxydes pérovskites par nanostructuration jusqu’à l’échelle de la monocouche”
  5. Bouaziz (2016-2020) : ” Intégration de matériaux ferroélectriques sur silicium pour réaliser un transistor ferroélectrique ”
  6. Wague (2014-2018) : ” Matériaux sans plomb micro-structurés pour la récupération d’énergie ”

 

Current Research engineer:

  1. Rousseau (2022-2024): “absorption spectroscopy for optical flux monitoring”

 

Current Post-doc :

  1. Moalla (2022-2024): “Functional oxide films for integrated photonics”

 

Former Post-docs (last 5 years):

  1. G. Yang (2020-2022) : “Ga2O3–Ti2O3 alloys for tunable photodetectors”

Current Projects

– Laboratoire commun INL / ST

– Marie Curie COFUND ECLAUSION project 2019-2024

 

Former Projects (last 5 years):

– Laboratoire commun INL / RIBER, 2013-2022

– ICPEI Nano2022 ST Microelectronics 2019-2022

– ANR VOLCONANO, 2019-2022 : « Contrôle par champ électrique de nanoaimant »

– ANR 2017 MITO, 2018-2021: « Premier micro module thermoélectrique à base d’oxydes »

– European project H2020 : 3eFERRO (« Energy Efficient Embedded Non-volatile Memory Logic based on Ferroelectric Hf(Zr)O2 »), 2018-2021

-ANR 2016 LILIT, 2016-2020

– Projet “NOTE” de la MITI CNRS, AAP “nouveaux matériaux” 2020 : « nouveaux oxydes thermoélectriques de type p »

– ANR 2016 DIAMWAFEL, 2016-2020

– Europeen Project TIPS, 2015-2018

– ANR 2015 GaZON, 2015-18

 

Collaborations :

International :

EPFL (Suisse), IBM Zürich (Suisse), ICMAB Barcelone (Espagne), Université d’Osaka (Japon), Tyndall Cork (Irlande), Université de Tokyo (Japon), UMI LN2 Sherbrooke (Canada), Université de Valencia (Espagne), KU Leuven (Belgique), DAS Photonics (Espagne), IHP (Allemagne), Université Jiatong Xi’an (Chine), NamLab (Allemagne), NIMP (Roumanie), Demokritos (Grèce).

National :

CEA Iramis Saclay, CEA-LETI Grenoble, CEA LIST Saclay, EPFL, synchrotron ESRF, FEMTO ST Besançon, GEMaC Versailles, LSPM Villetaneuse, Inst. Néel Grenoble, IES Montpellier, , IEMN Lille, ILM Lyon, CETHIL Lyon, IMEC-LAHC Grenoble, IMN Nantes, IRCELYON Villeurbanne,), LGEF Lyon, LSPM, RIBER, Synchrotron SOLEIL, SPMS Ecole Centrale Paris Chatenay Malabry, STMicroelectronics, CEA Iramis Saclay, C2N Palaiseau, IM2NP Marseille.

INL CNRS
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