The group III wurtzite nitrides have been revolutionizing the physics of semiconductors for more than two decades after that high quality materials could be grown and silicon n-type and magnesium p-type were realized at the end of the eighties. Based on this, candela class blue light emitting diodes and blue lasers were realized and commercialized. These triggered solid-state lighting and Blu-Ray DVD technology. Besides this massive arrival of optical devices on the market, a lot of basic physics phenomena inherent to the wurtzite symmetry were discovered or clarified, at least quantitatively framed. This was, and still is, of paramount importance for improving the performances of the nitride-based devices. I will review the different steps that paved the way of this breakthroughs and I will discuss the important issues that still have to be overcome in the next years: filling the green gap and realizing high luminosity amber or red light-emitting diodes in the one hand, designing and growing ultra violet light emitters in the other hand. The drawbacks inherent to the materials such as Auger non-radiative recombination processes will be discussed as well as the potentialities of growth on high Miller index surfaces for bypassing the deleterious Quantum Confined Stark Effect, for reducing the dislocation densities and for improving the performances of the generations of devices in the next years. The Nano-LEDs based on one-dimensional nitride crystals will be discussed as well as Nano lasers. Then, I will show results obtained regarding nitride quantum dots and single photon emitters, which are now grown on a large variety of surfaces, sometimes embedded into micro-cavities. At the end I will dedicate a few minutes to the presentation of boron nitride, a layered compound. Its physics is becoming a hot topics and one of the pioneers of the growth of nitrides speaks of it in terms of " the next guy".

We study the optomechanical coupling of a oscillating effective mirror with a Rydberg atomic gas, mediated by the dynamical atom-mirror Casimir-Polder force. This coupling may produce a near-field resonant atomic excitation whose probability scales as $\propto (d^2\;a\;n^4\;t)^2/z_0^8$, where $z_0$ is the average atom-surface distance, $d$ the atomic dipole moment, $a$ the mirror's effective oscillation amplitude, $n$ the initial principal quantum number, and $t$ the time. We propose an experimental configuration to realize this system with a cold atom gas trapped at a distance $\sim 2\cdot10 \, \mu$m from a semiconductor substrate, whose dielectric constant is periodically driven by an external laser pulse, hence realizing en effective mechanical mirror motion due to the periodic change of the substrate from transparent to reflecting. For a parabolic gas shape, this effect is predicted to excite about $\sim 10^2$ atoms of a dilute gas of $10^3$ trapped Rydberg atoms with $n=75$ after about $0.5 \,\mu \mbox{s}$, hence high enough to be detected in typical Rydberg gas experimental conditions.

We report on room-temperature plasmonic detection of sub-terahertz radiation by InAlAs/InGaAs/InP high electron mobility transistors with an asymmetric dual-grating-gate structure. Maximum responsivities of 22.7 kV/W at 200 GHz and 21.5 kV/W at 292 GHz were achieved under unbiased drain-to-source condition. The minimum noise equivalent power was estimated to be 0.48 pW/Hz0.5 at 200 GHz at room temperature, which is the record-breaking value ever reported for plasmonic THz detectors. Frequency dependence of the responsivity in the frequency range of 0.2-2 THz is in good agreement with the theory.

This study aims to investigate the influence of interlayer cation alkali metal series (Li+, Na+, K+, Rb+, Cs+) and alkali earth metal (Mg2 +, Ca2 +, Ba2 +) on adsorption of model proteins (lysozyme and bovine serum albumin). The localizations of both proteins and their conformational modifications in the interlayer space of the natural clay mineral were studied by X-ray diffraction, transmission electronic microscopy and fluorescence experiments. Based on Langmuir model isotherms, a strong influence of interlayer cation on maximum adsorbed amount and adsorption equilibrium constant has been observed. However the usual kosmotrope/chaotrope classification cannot be used to describe protein adsorption.

Wheat storage gluten proteins are among the most complex proteins families comprising at least fifty different proteins, with extremely broad polymorphisms. Wheat gluten proteins are moreover largely insoluble in water, rendering their study difficult. Gluten proteins are responsible for the remarkable viscoelastic properties of dough. However despite extensive studies over more than 200 years, in order to provide structural and mechanistic basis for the improvement of the viscoelastic properties of dough and of the quality of resulting food products, there is still a crucial need to understand supramolecular organization of gluten proteins. We have proposed a novel extraction protocol that allows for the first careful structural and rheological analysis of gluten protein suspensions over a wide range of protein concentrations. Our system appears therefore as a unique model system to investigate the supramolecular organization of gluten proteins and its impact on the viscoelastic properties of gluten gels. Rheological measurements show a spontaneous and very slow and concentration-dependent gelation of the samples which can be rationalized using percolation models. Consistently, scattering data highlight a hierarchical structure strikingly similar to that of polymeric gels, thus providing some factual knowledge to rationalize the viscoelastic properties of wheat gluten and their assemblies.

Wheat storage gluten proteins are among the most complex proteins families comprising at least fifty different proteins, with extremely broad polymorphisms. Wheat gluten proteins are moreover largely insoluble in water, rendering their study difficult. Gluten proteins are responsible for the remarkable viscoelastic properties of dough. However despite extensive studies over more than 200 years, in order to provide structural and mechanistic basis for the improvement of the viscoelastic properties of dough and of the quality of resulting food products, there is still a crucial need to understand supramolecular organization of gluten proteins. We have proposed a novel extraction protocol that allows for the first careful structural and rheological analysis of gluten protein suspensions over a wide range of protein concentrations. Our system appears therefore as a unique model system to investigate the supramolecular organization of gluten proteins and its impact on the viscoelastic properties of gluten gels. Rheological measurements show a spontaneous and very slow and concentration-dependent gelation of the samples which can be rationalized using percolation models. Consistently, scattering data highlight a hierarchical structure strikingly similar to that of polymeric gels, thus providing some factual knowledge to rationalize the viscoelastic properties of wheat gluten and their assemblies.

Diffusion hyper-Raman dans les systèmes désordonnés : verres et relaxeurs ferroélectriques