Stages Master 1 / Master 2

Imaging of charged ferroelectric domain walls for high density storage media

Downscaling of memory devices for ultra-high storage densities and low power consumption is a major challenge for post-CMOS electronics in order to implement new functionalities. Domain wall (DW) engineering in ferroic materials is one possible route where the DW rather than the bulk material becomes the active element. The challenge then is to predict and control the nanoscale DW functionality.
Charged domain walls (CDWs) in ferroelectric (FE) materials appear as a true, new paradigm for post-CMOS electronics precisely because they can be understood as nanometric mobile metallic conductors separated by highly insulating dielectric regions. They support currents nine orders of magnitude greater than in the intervening insulating domains. However, their high electrostatic energy makes them instable and a specific preparation method is necessary.

For more information:

Internship_Walls_CEA_2018.pdf

X-ray photoelectron diffraction study of structural phases in epitaxially strained ferroelectric thin films

A fundamental property of ferroelectric (FE) materials is their electrically switchable spontaneous polarization below the Curie temperature, which has driven promising applications of such materials as nonvolatile memory storage devices and sensors. Structural changes in thin films can modify the ferroelectric state and thus the performance of these materials in nanoelectronic devices, chemical sensors or photovoltaic cells. The polarization state may be chemically switched by annealing under oxygen and epitaxial strain can engineer completely new FE phases.

X-ray Photoelectron Diffraction (XPD) combines the chemical sensitivity of core level photoemission with local order sensitivity around the emitting atom. The photoemission intensity is measured as a function of angle above the sample, giving information on interatomic distances, bond angles and chemical states. It is therefore ideally suited to measure the surface distortions in the atomic structure of epitaxial FE films. IRAMIS has recently installed a new, high angular resolution XPD experiment with fully automatic data acquisition system.

For more information:

Sujet_XPD_CEA_an.pdf

Thèses

Caracterisation et contrôle électro-mécanique des parois de domaines chargées

Ferroelectrics (FE) materials have important applications for non-volatile memories because of their fast switching and long retention. Insulating by nature, the recent discovery of FE domain wall (DW) conduction has triggered a new era: DWs exhibit very different electronic properties than the parent materials and can be controlled (written or erased) by application of electric fields. DWs are intrinsically nano-sized objects with a thickness of few unit cells, and therefore highly scalable. Their variable conductivity opens the door to numerous applications where the electronic properties can be tuned both through the DW density and conductivity. The conceptual breach is based on the wall itself becoming the active element of the device.

Nous avons déjà le financement de la thèse, qui commencera en Octobre 2018.

Pour plus d'informations :

DomainWalls_2018_CEAThalesICMMO.pdf

Link to the Ecole Doctorale ED PIF:
Subject n° 95.

Characterizatrion of the interface electronic structure of ultra-thin ferroelectric HfZrO2 films for low power, CMOS-compatible, non-volatile memories

Link to the Ecole Doctorale ED PIF:
Subject n° 94.

Stages Post-Doctoraux

Propositions déposées tout au long de l'année