Structures that strongly confine the photons on the scale of the light wavelength have been studied in semiconductor physics for about 20 years, giving rise to a wealth of fundamental studies exploiting the reinforced light-matter (both linear and nonlinear) interaction. Most studies were done in well mastered III-V material systems, which however suffer from some drawbacks such as a low exciton binding energy, low barrier potentials in heterostructures and a transparency window limited to the near infrared. Semiconductors of the III-N family have quite peculiar properties such as a large excitonic binding energy and a transparency window that extends to 200 nm. They are the dominant material family for the fabrication of UV-blue-green optoelectronic devices (laser diodes and light-emitting diodes) as well as for white light production. Nitrides are already massively used for high density optical storage and display light sources but shorter wavelength optoelectronic devices are also potentially very interesting for biochemical sensors, purification, disinfection and medical diagnosis. Interestingly, a current trend consists in integrating III-N materials on silicon. For these reasons, III-N materials are thus expected to play a significant role in novel photonic systems and, in this respect they are very good candidates to probe light-matter interaction in photon confining structures. It is however notorious that III-N semiconductors are difficult to process and this technological drawback has hindered achievements in highly confined optical structures. It is the aim of the QUANONIC project to probe quantum optical and nonlinear effects in AlGaN based high optical quality microdisks and photonic crystal (PC) structures. Based on the know-how of the consortium to fabricate and to probe III-N based microcavities, several goals will be pursued and if successful will represent major breakthroughs for the development of novel optoelectronic devices integrated on silicon. Goal 1 : Microlaser and strong coupling at UV wavelengths in III-N microcavities. Fabrication of optical resonators having high quality factors is now mastered by the consortium. The next issue to address to reach lasing is the optimization of the active region in order to get high gain active medium: our strategy is twofold. i) We will seek to grow GaN/AlN quantum dots (QD) with high oscillator strength and high areal density. A detailed study of microlasing and Purcell effect will be made. ii) By exploiting the large oscillator strength of III-N excitons, high quality factor microcavities will be designed for photon-exciton strong coupling. We shall explore the conditions for strong coupling, both for confined modes and for extended modes in III-N photonic crystals. The ultimate goal will be to reach polariton lasing. Goal 2 : Frequency conversion in III-N photon confining structures for deep UV sources. Thanks to a much wider transparency window than conventional semiconductors and to large nonlinear coefficients, III-N are very good candidates for frequency conversion in confined structures. The photonic crystal geometry allows for large field intensities (cavity enhanced frequency conversion) and also for the tailoring of the refractive properties. Original phase-matching conditions will be demonstrated experimentally, such as backward second harmonic generation (SHG) and “all angle” SHG that are very difficult or impossible to obtain in larger scale periodically poled nonlinear materials. As a final and ambitious objective of the project, we propose an investigation of a compact coupling of semiconductor lasers and frequency converting cavities that enlightens the potentialities of our approach for forthcoming UV optoelectronics. The integration of nitride laser emission and frequency doubling in a III-N photonic structure represents a realistic opportunity to demonstrate an all-semiconductor compact optical source operating in the 200-250 nm wavelength range.

Phase Change Random Access Memories (PCRAM), which are based on the reversible amorphous-crystalline transition in phase change materials (PCMs), constitute a very promising alternative to Flash technology, which is reaching fundamental limits. One of their key advantages is their scalability but, for ultimate miniaturization, energy consumption is critical and a promising solution is the geometrical confinement of the memory points. Mastering this with PCMs at ultimate dimensions (typically 5 nm) is, however, a real challenge, which calls for a fundamental understanding of the interplay between strain (the amorphous-to-crystal transition is accompanied by density increase of several %) and interface energies at the nanoscale. The objective of the SESAME project is to study the influence of strain and size on the PCM phase transition at ultimate dimensions. To address these issues we will use advanced in situ characterization techniques applied to ultra-thin layers, confined nanostructures and nanoclusters in order to investigate the early stages of phase transition and also to measure local strains and microstructure changes at crystallization. Five partners with complementary know-how will participate in the project: IM2NP-Marseille, CEA-LETI-Grenoble, CEA-INAC-Grenoble, synchrotron SOLEIL – St Aubin, CINaM-Marseille. The SESAME project will be organized along 5 tasks: 1. Coordination, 2. Sample preparation and characterization, 3. High resolution synchrotron X-ray scattering, 4. Transmission Electron Microscopy (TEM), 5. Simulation. Thin/ultra-thin GeTe and Ge2Sb2Te5 (GST) PCM films and PCM materials in confined structures will be prepared at CEA-LETI. Various thickness (100 to 5 nm), size (down to 10 nm width) and capping materials (Ta, TaN, Ta2O5, SiN, SiO2, Ti, TiN …) will be studied. CEA-INAC has the unique capability of preparing sub-10 nm GeTe and GST clusters by gas phase condensation. This will allow us to address the ultimate sizes, far beyond existing capabilities of lithography. Clusters with different composition or doping will be embedded in matrices with various thermo mechanical properties in order to evaluate the impact of mechanical stress on PCM clusters properties. Preliminary in situ sample characterizations will be performed at CEA: in situ ellipsometry, reflectivity, Raman spectroscopy or four-point-probe resistivity measurements. On these well-characterized samples unique in situ High-resolution synchrotron x-ray scattering and state-of-the-art transmission Electron microscopy (TEM) investigations will be performed. An original combination of resistance, X-ray diffraction and X-ray reflectivity that allows correlating structural and electrical PCM properties upon crystallization has been developed jointly by IM2NP and ESRF and will be used at synchrotron SOLEIL to characterize in situ the phase transition of ultrathin PCMs. Also the in situ combination of X-ray diffraction and optical curvature measurements developed jointly by IM2NP and DiffAbs beamline at SOLEIL will allow for an in-depth understanding of the mechanics involved in the amorphous-to-crystal transition. State-of-the-art TEM performed at CEA-INAC and CEA-LETI will bring valuable knowledge on local distribution of elements, defects and strains. In situ TEM observations during crystallization will offer invaluable information on the nucleation sites for crystallization. It is worth noting that these highly original in situ techniques (based either on TEM or Synchrotron radiation) will be used also to investigate structural changes in the amorphous phase. The issue of resistance drift in the amorphous phase is a key point for the stability of stored information in the memory cell. Atomistic simulations (Density Functional Theory, Molecular Dynamics) will be performed at CINaM in order to simulate the atomistic structure and the properties (structural, electronic, spectroscopic) of phase change materials in amorphous and crystalline form.

The UNESCOS project explores new frontiers for condensed matter physics: the interplay between new states of matter and superconductivity in strongly correlated electron systems. Unlocking this fundamental issue will provide materials scientists with new insights on how to design and produce new superconductors operating at higher temperature. This line of research will ultimately lead to technological breakthrough, new and more efficient avenues to produce, store and transmit electricity. Dealing with the enigmatic “pseudogap” state out of which high temperature superconductivity emerges in the phase diagram of cuprate superconductors, UNESCOS focuses on the study of unconventional charge density instabilities and aim to develop the concept of unconventional superconductivity driven by quantum criticality. The UNESCOS project is a jointed research program involving physicists from LNCMI, LLB and IPhT, whose works have received an important visibility in the last few years, bringing new concepts to this field: (i) Fermi surface reconstruction and stabilization of a charge density wave order under magnetic field, (ii) observation of an intra-unit-cell magnetic order in the pseudogap state using polarized neutron scattering technique, (iii) condensations of new phases, potentially responsible for the pseudogap state, induced by antiferromagnetic quantum fluctuations. Taken separately these works may seem to promote different and apparently conflicting physical pictures. The UNESCOS project takes up the challenge to bridge together phenomena, previously supposed unrelated and promote the emergence of a unified theoretical picture within the framework of a new theory for the pseudogap state implying a multicomponent order parameter mixing a quadrupolar density wave order and d-wave superconductivity. This new, controlled and predictive theory will be developed and specific calculations will be performed to predict and explain new experimental observations that will be carried out within the project. Indeed the theoretical work will be performed in synergy with thermodynamic (sound velocity), diffraction and spectroscopy (neutron and X-ray) measurements providing key information on the microscopic nature and symmetry of the anomalous electronic phenomena. These experiments will require technologies that are available only in large facilities (Neutron source, Synchrotron, High-Magnetic-Field laboratory).

We propose the development of a new generation of an integrated ion source system for the production of very pure radioactive ion beams at low energy, including isomeric beams. This ion source is also, in its own right, an experimental tool for laser spectroscopy. The Rare Elements in-Gas Laser Ion Source and Spectroscopy device will be installed at the S3 spectrometer, currently under construction as part of the SPIRAL-2 facility at the GANIL laboratory in Caen. Thus, REGLIS3 will be a source for the production of new and pure radioactive ion beams at low energy as well as a spectroscopic tool to measure nuclear hyperfine interactions, giving access to charge radii, electromagnetic moments and nuclear spins of exotic nuclei so far not studied. It consists of a gas cell in which the heavy-ion beam coming from S3 will stopped and neutralized, coupled to a laser system that assures a selective re-ionisation of the atoms of interest. Ionization can be performed in the gas cell or in the gas jet streaming out of the cell. A radiofrequency quadrupole is added to capture the photo-ions and to guide them to the low-pressure zone thereby achieving good emittance of the produced low-energy beam that will be sent to a standard measurement station. Owing to the unique combination of such a device with the radioactive heavy ion beams from S3, a new realm of unknown isotopes at unusual isospin (N/Z ratio, refered to as exotic isotopes) will become accessible. The scientific goals focus on the study of ground-state properties of the N=Z nuclei up to the doubly-magic 100Sn and those of the very heavy and superheavy elements even beyond fermium. Once routine operation is achieved the beams will be used by a new users community as e.g. decay studies and mass measurements. The goal of the proposal is to develop this new, efficient, and universal source for pure, even isomeric, beams and for pioneering high-resolution laser spectroscopy that will overcome the present experimental constraints to study very exotic nuclei.

The present project is put into the context of the international projects ITER and DEMO aiming at managing nuclear fusion to produce energy. In tokamaks (nuclear fusion reactors), a hot plasma composed of deuterium and tritium nuclei is magnetically confined to achieve fusion. The heating of the plasma is mainly obtained by the injection of high-energy deuterium neutral beams, coming from the neutralization of high-intensity D- negative-ion beams. D- negative-ions are produced in a low-pressure plasma source and subsequently extracted and accelerated. The standard and most efficient solution to produce high negative-ion current uses cesium (Cs) injection and deposition inside the source to enhance negative-ion surface-production mechanisms. However, ITER and DEMO requirements in terms of extracted current push this technology to its limits. The already identified drawbacks of cesium injection are becoming real technological and scientific bottlenecks, and alternative solutions to produce negative-ions would be highly valuable. The first objective of the present project is to find an alternative solution to produce high yields of H-/D- negative-ions on surfaces in Cs-free H2/D2 plasmas. The proposed study is based on a physical effect discovered at PIIM in collaboration with LSPM, namely the enhancement of negative-ion yield on boron-doped-diamond at high temperature. The yield increase observed places diamond material as the most up to date relevant alternative solution for the generation of negative-ions in Cs-free plasmas. The project aims at fully characterizing and evaluating the relevance and the capabilities of diamond films (intrinsic and doped polycrystalline, single crystal as well as nanodiamond films…) as negative-ion enhancers in a negative-ion source. The second objective is to investigate diamond erosion under hydrogen (deuterium) plasma irradiation, with two main motivations. First, material erosion could be a limitation of the use of diamond as a negative-ion enhancer in a negative-ion source and must be evaluated. Second, the inner-parts of the tokamaks receiving the highest flux of particles and power are supposed to be made of tungsten, but its self-sputtering and its melting under high thermal loads are still major issues limiting its use. It has been shown in the past by one of the partners that diamond is a serious candidate as an efficient alternative-material for fusion reactors. Therefore, diamond erosion in hydrogen plasmas will also be investigated from this perspective. At the moment when all the efforts are put on tungsten, maintaining a scientific watch on backup solutions for tokamak materials is crucial. The project associates partners with complementary expertise in the field of plasma-surface interactions on the one hand, and diamond deposition and characterization on the other hand. Furthermore, in order to span the gap between fundamental science and real-life applications, negative-ion surface-production and diamond erosion will be studied in laboratory plasmas (PIIM in collaboration with LSPM ) as well as in real devices (Cybele negative-ion source at IRFM and Magnum-PSI experiment at DIFFER ). PIIM: Physique des Interactions Ioniques et Moléculaires, Université Aix-Marseille, CNRS LSPM: Laboratoire des Sciences des Procédés et des Matériaux, CNRS, Université de Paris 13 IRFM: Institut de Recherche sur la Fusion Magnétique, Commissariat à l’Energie Atomique, Cadarache DIFFER: Dutch Institute For Fundamental Energy Research, The Netherlands