Seminars
Correlated Atom Probe Tomography and optical spectroscopy analyses of nitride nanostructures
, C2N-site Orsay,Seminars
In this seminar I will present our work on nanoscale analyses of nitride nanostructures such as InGaN/GaN quantum wells (QWs) in nanowires and GaN/AlN Stranski-Krastanov quantum dots (QDs). These nanostructures are investigated by correlating their structural properties assessed by Atomic Probe Tomography and STEM with their optical signature addressed by micro-photoluminescence and time-resolved photoluminescence. Experimental results are compared with 3D effective mass modeling, which account for the experimental 3D composition of the nanostructures. The multi-microscopy approach allows for studying different system dependent features, namely the effect of stacking faults on the optical properties of single InGaN/GaN QWs (illustrated in Fig. 1) and the influence of GaN/AlN QDs morphology and thickness fluctuations on transition energies, charge carriers localization, and biexciton-exciton cascade processes. The ensemble of the results obtained for the two III-N nanostructures systems shows how the developed approach ensures the best exploitation of the information obtained from the different analyses, allowing for a precision of characterization, which can be hardly matched by other techniques.
The Wonder of Nanotechnology
, C2N - site de Marcoussis,Seminars
Nature offers us a full assortment of atoms, but nanoengineering is required to put them together in an elegant way to realize functional structures not found in nature. A particular rich playground for nanotechnology is the so-called III-V semiconductors, made of atoms from columns III and V of the periodic table, and constituting compounds with many useful optical and electronic properties in their own right. Guided by highly accurate simulations of the electronic structure, modern semiconductor optoelectronic devices are literally made atom by atom using advanced growth technology such as molecular beam epitaxy and metal organic chemical vapor deposition to combine these materials in ways to give them new proprieties that neither material has on its own. Modern mastery of materials growth and characterization with the help of such techniques allows high-power and highly efficient functional devices to be made, such as those that convert electrical energy into coherent light or detect light of any wavelength and convert it into an electrical signal. This talk will present the latest world-class research breakthroughs that have brought quantum engineering to an unprecedented level, creating light detectors and emitters over an extremely wide spectral range from 0.2 to 300 microns. Contact: Fabrice
PT-symmetric systems : from quantum mechanics to nonlinear physics
, C2N - site Orsay- salle P. Grivet RdC pièce 44,Seminars
Nonlinear phenomena in media obeying parity-time (PT) symmetry, i.e. having dissipation and gain delicately balancing each other, attract rapidly growing attention due to their relevance to nonlinear optics, to the theory of Bose-Einstein condensate, as well as to other numerous physical applications. Starting with brief overview of the basics of PT-symmetric quantum mechanics I will discuss recent developments in the theory of nonlinear PT symmetric physics. The main focus will be on the models appearing in PT-symmetric optics including discrete PT-symmetric optics and nonlinear wave phenomena of guided modes including bright and dark solitons, breathers, rogue waves, and vortices.
Thermotronics: toward circuits for the thermal light
, C2N-Marcoussis,Seminars
The ability to control electric currents in solids using diodes and transistors is undoubtedly at the origin of the main developments in modern electronics, which have revolutionized the daily life in the second half of 20th century. Surprisingly, until the year 2000 no thermal counterpart for such a control had been proposed. Since then, based on pioneering works on the control of phononic heat currents new devices were proposed which allow for the control of heat fluxes carried by photons rather than phonons or electrons. In this presentation I will discuss the recent advances in the field of thermal energy control with photons.
Light matter interaction between a 2DES and a photonic cavity: quantum Hall polaritons
, C2N - site de Marcoussis,Seminars
Light-matter interaction has played a central role in engineering and manipulating new states of matter. For instance, reversible coupling of excitons and photons in a microcavity has been used to study condensation and superfluidity of cavity polaritons. I will present experiments on a highmobility two-dimensional electron gas (2DEG) embedded inside a microcavity, combining the physics of correlated many-body states of a 2DEG with the methods of cavity quantum electrodynamics. Tuning the cavity into resonance with the electron gas when magnetic field Bz > 0, we exhibit strongly correlated polariton modes that show unique signatures of both integer and fractional quantum Hall effects. We demonstrate that the polarization dependent normal-mode splitting of quantum Hall polaritons provides a direct way to measure the spin-polarization of quantum Hall states, which constitutes a powerful method to complement transport spectroscopy with the advantages of a minimally invasive local probe. The system is potentially of interest for realizing strongly correlated photonic systems since it may be possible to exploit strong electron density dependence of 2DEG-polariton splitting to enhance polariton-polariton interactions.
(in french) "Silicene, germanene, and something in between?"
None, C2N - site de Marcoussis- Salle Planel, NoneSeminars
(in french) L'espace-temps invariant : oublions Lorentz, Maxwell, Newton, pour mieux les retrouver
None, Site de Marcoussis - bât. D1, salle R. Planel, NoneSeminars
Thermotronics : toward circuits for the thermal light
, /!\ Repoussé à septembre /!\ Site de Marcoussis,Seminars
Thermotronics : toward circuits for the thermal light
(in french) MoS2 et ses cousins: Nouveaux Matériaux Bidimensionnels aux Propriétés Prometteuses
None, Site Marcoussis - bât. D1, Salle R. Planel, NoneSeminars