High temperature power electronics has become possible with the recent availability of silicon carbide devices. This material, as other wide-bandgap semiconductors, can operate at temperatures above 500°C, whereas silicon is limited to 150-200°C. Applications such as transportation or a deep oil and gas wells drilling can benefit. A few converters operating above 200°C have been demonstrated, but work is still ongoing to design and build a power system able to operate in harsh environment (high temperature and deep thermal cycling).

Single-Wall Carbon Nanotubes (SWNTs) are among the very few candidates for single-photon sources operating in the telecom bands since they exhibit large photon antibunching up to room temperature [1][2][3][4][5]. However, coupling a nanotube to a photonic structure is highly challenging because of the random location and emission wavelength in the growth process [6][7][8][9]. Here, we demonstrate the realization of a widely tunable single-photon source by using a carbon nanotube inserted in an original repositionable fiber micro-cavity: we fully characterize the emitter in the free-space and subsequently form the cavity around the nanotube. This brings an invaluable insight into the emergence of quantum electrodynamical effects. We observe an efficient funneling of the emission into the cavity mode with a strong sub-Poissonian statistics together with an up to 6-fold Purcell enhancement factor. By exploiting the cavity feeding effect on the phonon wings, we locked the single-photon emission at the cavity frequency over a 4 THz-wide band while keeping the mode width below 80 GHz. This paves the way to multiplexing and multiple qubit coupling.Coupling a carbon nanotube to a photonic resonator in a reliable way is highly desirable both for technological developments in view of quantum cryptography or quantum computation and for academical studies since nanotubes behave like an original nano-emitter showing an hybrid 1D-0D electronic behavior [10]. In addition, the low-cost, the high integrability and the possible electrical excitation of nanotubes [11] are attractive assets in such perspectives. However, due to the lack of control of the current growth or deposition processes, current attempts rely on random spectral and spatial matching between a resonator (micro-discs [12] or photonic crystals [13]) and randomly deposited nanotubes, leading to a very limited fabrication yield. This constrain becomes especially stringent when a high coupling between the emitter and the cavity is sought, which requires narrow spectral features.In this work, we propose an original approach where the nanotube is fully characterized in free-space by regular low-temperature micro-photoluminescence (micro-PL) spectroscopy and where a micro-cavity is subsequently formed around the emitter by approaching a concave dielectric mirror micro-engineered at the apex of an optical fiber. This geometry brings an unprecedented flexibility giving a built-in spectral and spatial matching, together with excellent quality factors and mode volumes [14]. Individual carbon nanotubes embedded in a polystyrene matrix were coupled to the cavity resulting in a strong brightening of the nanotube of more than an order of magnitude, bringing evidence for the relevance of exploiting cavity quantum electrodynamical (CQED) effects to enhance the photonic properties of carbon nanotubes. By means of time-resolved measurements we were able to investigate directly the cavityenhanced emission rate and found a corresponding Purcell factor F p of up to 5. In the same tim...

We addressed the carrier dynamics in so-called G-centers in silicon (consisting of substitutional-interstitial carbon pairs interacting with interstitial silicons) obtained via ion implantation into a silicon-on-insulator wafer. For this point defect in silicon emitting in the telecommunication wavelength range, we unravel the recombination dynamics by time-resolved photoluminescence spectroscopy. More specifically, we performed detailed photoluminescence experiments as a function of excitation energy, incident power, irradiation fluence and temperature in order to study the impact of radiative and non-radiative recombination channels on the spectrum, yield and lifetime of G-centers. The sharp line emitting at 969 meV ($\sim$1280 nm) and the broad asymmetric sideband developing at lower energy share the same recombination dynamics as shown by time-resolved experiments performed selectively on each spectral component. This feature accounts for the common origin of the two emission bands which are unambiguously attributed to the zero-phonon line and to the corresponding phonon sideband. In the framework of the Huang-Rhys theory with non-perturbative calculations, we reach an estimation of 1.6$\pm$0.1 $\angstrom$ for the spatial extension of the electronic wave function in the G-center. The radiative recombination time measured at low temperature lies in the 6 ns-range. The estimation of both radiative and non-radiative recombination rates as a function of temperature further demonstrate a constant radiative lifetime. Finally, although G-centers are shallow levels in silicon, we find a value of the Debye-Waller factor comparable to deep levels in wide-bandgap materials. Our results point out the potential of G-centers as a solid-state light source to be integrated into opto-electronic devices within a common silicon platform

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Temperature dependant properties of wide band gap semiconductors have been used to calculate theoretical specific on-resistance, breakdown voltage, and thermal run away temperature in SiC, GaN and diamond, and Si vertical power devices for comparison. It appears mainly that diamond is interesting for high power devices for high temperature applications. At room temperature, diamond power devices should be superior to SiC only for voltage higher than 30-40 kV, due to the high energy activation of the dopants.

Silicon carbide (SiC) power devices can operate at much higher junction temperature than those made of silicon. However, this does not mean that SiC devices can operate without a good cooling system. To demonstrate this, the model of a Merged PiN Schottky (MPS) SiC diode is presented, and its parameters are identified with experimental measurements. This model is then used to study the ruggedness of the diode regarding the thermal run-away phenomenon. Finally, it is shown that where a purely unipolar diode would be unstable, the MPS structure brings increased stability.

Host specialization plays a key role in the extreme diversification of phytophagous insects. Whereas proximate mechanisms of specialization have been studied extensively, their consequences for species divergence remain unclear. Preference for, and performance on hosts are thought to be a major source of divergence in phytophagous insects. We assessed these major components of specialization in two moth species, the European corn borer (ECB) and the Adzuki bean borer (ABB), by testing their oviposition behaviour in different conditions (choice or no-choice set-ups) and their performances, by reciprocal transplant at the larval stage on the usual host and an alternative host plant. We demonstrated that both ABB and ECB have a strong preference for their host plants for oviposition, but that relative larval performances on the usual host and an alternative host differed according to the experiment and the trait considered (weight or survival). Finally, we show for the first time that the preference for maize in ECB conceals a strong avoidance of mugwort. The differences in performance, attraction and avoidance between ECB and ABB are discussed in the light of the underlying mechanisms and divergence process.

SiC is currently an important topic in power devices. This new technology leads to lower power losses, faster switching, and higher working temperature. The design of SiC power devices requires the integration of edge termination techniques to obtain a high blocking voltage. The mesa structure approach is one wellestablished method. It could be used alone or in combination with a Junction Termination Extension (JTE). The mesa consists of a structure that removes material around the pn-junction. Due to the strong Si-C bonds, conventional chemical-wet etching solutions are inefficient on SiC, so plasma methods are required to etch SiC.The presented work is based on the use of an RIE reactor with an SF 6 /O 2 plasma. Its geometry structure and parameters were optimized. An etch rate of 0.35 µm/min was obtained without any trenching phenomenon. Trenches deeper than 10 µm deep were realized with a nickel etching mask that shows a high selectivity. AFM analysis revealed an etched surface as smooth as the initial one.