Faraday optical isolator in the 9.2 μ\mum range for QCL applications

We have fabricated and characterized a n-doped InSb Faraday isolator in the mid-IR range (9.2 $\mu$m). A high isolation ratio of $\approx$30 dB with a transmission over 80% (polarizer losses not included) is obtained at room temperature. Further possible improvements are discussed. A similar design can be used to cover a wide wavelength range (lambda ~ 7.5-30 $\mu$m)

Mid-IR plasmonic compound with gallium oxide toplayer formed by GaSb oxidation in water

The oxidation of GaSb in aqueous environments has gained interest by the advent of plasmonic antimonide-based compound semiconductors for molecular sensing applications. This work focuses on quantifying the GaSb–water reaction kinetics by studying a model compound system consisting of a 50 nm thick GaSb layer on a 1000 nm thick highly Si-doped epitaxial grown InAsSb layer. Tracing of phonon modes by Raman spectroscopy over 14 h of reaction time shows that within 4 h, the 50 nm of GaSb, opaque for visible light, transforms to a transparent material. Energy-dispersive x-ray spectroscopy shows that the reaction leads to antimony depletion and oxygen incorporation. The final product is a gallium oxide. The good conductivity of the highly Si-doped InAsSb and the absence of conduction states through the oxide are demonstrated by tunneling atomic force microscopy. Measuring the reflectivity of the compound layer structure from 0.3 to 20 μm and fitting of the data by the transfer-matrix method allows us to determine a refractive index value of 1.6 ± 0.1 for the gallium oxide formed in water. The investigated model system demonstrates that corrosion, i.e. antimony depletion and oxygen incorporation, transforms the narrow band gap material GaSb into a gallium oxide transparent in the range from 0.3 to 20 μm

Indium antimonide photovoltaic cells for near-field thermophotovoltaics

International audienceIndium antimonide photovoltaic cells are specifically designed and fabricated for use in a near-field thermophotovoltaic device demonstrator. The optimum conditions for growing the p-n junction stack of the cell by means of solid-source molecular beam epitaxy are investigated. Then processing of circular micron-sized mesa structures, including passivation of the side walls, is described. The resulting photovoltaic cells, cooled down to around 77 K in order to operate optimally, exhibit excellent performances in the dark and under far-field illumination by thermal sources in the [600-1000] °C temperature range. A short-circuit current beyond 10 µA, open-circuit voltage reaching almost 85 mV, fill factor of 0.64 and electrical power at the maximum power point larger than 0.5 W are measured for the cell with the largest mesa diameter under the highest illumination. These results demonstrate that these photovoltaic cells will be suitable for measuring a near-field enhancement of the generated electrical power

Fano-like resonances sustained by Si doped InAsSb plasmonic resonators integrated in GaSb matrix

By using metal-free plasmonics, we report on the excitation of Fano-like resonances in the mid-infrared where the Fano asymmetric parameter, q, varies when the dielectric environment of the plasmonic resonator changes. We use silicon doped InAsSb alloy deposited by molecular beam epitaxy on GaSb substrate to realize the plasmonic resonators exclusively based on semiconductors. We first demonstrate the possibility to realize high quality samples of embedded InAsSb plasmonic resonators into GaSb host using regrowth technique. The high crystalline quality of the deposited structure is confirmed by scanning transmission electron microscopy (STEM) observation. Second, we report Fano-like resonances associated to localized surface plasmons in both cases: uncovered and covered plasmonic resonators, demonstrating a strong line shape modification. The optical properties of the embedded structures correspond to those modeled by finite-difference time-domain (FDTD) method and by a model based on Fano-like line shape. Our results show that all-semiconductor plasmonics gives the opportunity to build new plasmonic structures with embedded resonators of highly doped semiconductor in a matrix of un-doped semiconductor for mid-IR applications

Epitaxy and characterization of InP/InGaAs tandem solar cells grown by MOVPE on InP and Si substrates

The integration of III-V multi-junction solar cells on Si substrates is currently one of the most promising possibilities to combine high photovoltaic performance with a reduction of the manufacturing costs. In this work, we propose a prospective study for the realization of an InP/InGaAs tandem solar cell lattice-matched to InP on a commercially available Si template by direct MOVPE growth. The InP top cell and the InGaAs bottom cell were firstly separately grown and optimized using InP substrates, which exhibited conversion efficiencies of 13.5% and 11.4%, respectively. The two devices were then combined in a tandem device by introducing an intermediate InP/AlInAs lattice-matched tunnel junction, showing an efficiency of 18.4%. As an intermediate step towards the realization of the tandem device on Si, the InP and InGaAs single junction solar cells were grown on top of a commercial InP/GaP/Si template. This transitional stage enabled to isolate and evaluate the effects of the growth of III-V on Si on the photovoltaic performance through the comparison with the aforementioned devices on InP. Each cell was electrically characterized by external quantum efficiency and dark and illuminated current-voltage under solar simulator. The material quality was also analyzed by means of X-ray diffraction, Atomic-Force Microscopy, Transmission Electron and Scanning Electron Microscopy. The III-V on Si devices showed efficiencies of 3.6% and 2.0% for the InP and InGaAs solar cells, respectively

Heterogeneous integration of GaInAsSb p-i-n photodiodes on a silicon-on-insulator waveguide circuit

We report the integration of GaInAsSb p-i-n photodiodes on a silicon-on-insulator waveguide circuit. The device operates with low dark current (1.13 mu A at -0.1 V) at room temperature. A high responsivity of 0.44 A/W is measured at 2.29 mu m. This yields 1.63 x 10(9) cmHz (1/2)/W of Johnson-noise-limited-detectivity

Semiconductor lasers

International audienc

Mid-Infrared Semiconductor Lasers

International audienc

RETRATO DE PRIMERA COMUNIÓN [Material gráfico]

Copia digital. Madrid : Ministerio de Educación, Cultura y Deporte, 201