Design and characterization of top-emitting microcavity light-emitting diodes

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High-efficiency single-photon detection in the microwave domain is a key enabling technology for various quantum applications. However, the extremely low energy of microwave photons presents a fundamental challenge, preventing direct photon-to-charge conversion as achieved in optical systems using semiconductors. Here, we demonstrate continuous microwave photon detection with an efficiency approaching 70% in the single-photon regime. We use a hybrid system comprising a gate-defined double quantum dot (DQD)

Halide perovskite solar cells have demonstrated a rapid increase in power conversion efficiencies. Understanding and mitigating remaining carrier losses in halide perovskites is now crucial to enable further increases to approach their practical efficiency limits. Recent observations in halide perovskites have revealed processes such as shallow carrier trapping, which give rise to an apparent non-radiative bimolecular channel that is difficult to distinguish from intrinsic radiative recombination. Here, we

Quantum emitters, such as quantum dots and organic molecules, are vital components in many modern optical devices, including displays and sensing systems. In the visible spectrum, these emitters are highly efficient in light emission, but their performance declines significantly with decreasing optical gap due to the energy-gap law, limiting their use especially for infrared applications. To overcome this, coupling them with plasmonic particles can significantly enhance light emission by leveraging field co

The synthesis of a new series of neutral bis[2-(2,4-difluorophen-2-yl)pyridine][1-(2-aryl)-3-methylimidazol-2-ylidene]iridium(III) complexes is reported. Each complex has been characterized by NMR spectroscopy, UV/Vis spectrophotometry, and cyclic voltammetry, and the photophysical properties examined in depth. Furthermore, two of the complexes have been characterized by single-crystal X-ray diffraction analysis. By systematically modifying the cyclometalating aryl group on the N-heterocyclic carbene (NHC)

We report on the growth by metalorganic vapor phase epitaxy of a InGaN/GaN resonant-cavity light emitting diode (RCLED) emitting at 454 nm and incorporating a 12-pair Al0.82In0.18N/GaN distributed Bragg reflector as bottom mirror. A(1-x)In(x)N layers with an Al content around x similar to 0.17 are lattice matched to GaN, thus avoiding strain-related issues in the subsequent active layers while keeping a high refractive index contrast of 7%, comparable to that achievable in the Al0.5Ga0.5N/GaN system. Device

Over the past decade a new family of optoelectronic devices has emerged whose performance is enhanced by placing the active device structure inside a Fabry–Perot resonantmicrocavity [P. E. Green, IEEE Spectrum 13 (2002)]. The increased optical field allows photodetectors to be made thinner and therefore faster, while simultaneously increasing the quantum efficiency at the resonant wavelengths. We have demonstrated a variety of resonant cavity enhanced (RCE) photodetectors in compound semiconductors [B. Yang

Doping of organic light-emitting devices using highly luminescent molecules is a well-established strategy to improve brightness, efficiency and lifetime or to adjust emission color and color purity. Laser dyes from the pyran-containing donor-acceptor family are particularly interesting for emission in the yellow and red spectral domain. In solution, these polar dyes show marked solvatochromic shifts in the absorption and emission. The fluorescence quantum efficiency also depends strongly on solvent polarit

We present a study on the improvement of the external Quantum Efficiency (QE) of Gallium-Nitride-based Light Emitting Diodes (LEDs) by the use of the Single Mirror (SMLED) design [N.E.J. Hunt et al., Electron. Lett. 28, 2169 (1992)]. Three different substrate emitting LEDs are compared by measurements and simulations. An increase in the external QE by more than a factor of two is demonstrated, due to the enhancement of the Light Extraction Efficiency for the SMLED design. Using the SMLED design leads to val

MOLED solves the dynamics of electrons and holes in multilayer organic light emitting diodes (OLED). The carriers are injected on the positive and negative electrodes of the device by tunneling through a potential barrier. Thermal excitation processes across the barrier are also included. In the interior of the device the electron-hole recombination occurs when the two carriers are close enough, according to a model inspired from the one of Langevin. A fraction of these recombined pairs gives photons. The c

Recombination dynamics in a variety of InGaN/GaN quantum systems has been studied by time resolved photoluminescence (PL). We have discovered that the time-decay of PL exhibits a scaling law: the nonexponential shape of this decay is preserved for quantum wells and quantum boxes of various sizes while their decay time varies over several orders of magnitude. To explain these results, we propose an original model for electron-hole pair recombination in these systems, combining the effects of internal electri

We have demonstrated ultrafast coherent control of excitons and exciton-polaritons in semiconductor quantum nanostructures. An InGaAs/AlGaAs multi-quantum-well Bragg structure and an AlGaAs/GaAs crescent-shaped quantum wire structure were used as samples for the control of the exciton-polariton and excitons in the nanostructure. In the multi-quantum-well Bragg sample, a two-stage decay due to the super-radiant exciton-polariton mode is clearly observed under the resonance conditions. Highly sensitive cohere

The photoluminescence (PL) and PL-excitation (PLE) spectra of InyCa1-yAs/AlxGa1-xAs compressively strained V-groove quantum wires (QWR's) are compared to that of lattice-matched GaAs/AlyGa1-xAs QWR's with the same wire geometry. The PL is preferentially polarized along the QWR axis and the PL anisotropy increases with increasing indium content y. The observed PLE anisotropy also increases with y at the ground subband transition but is nearly independent of excited subband indices, unlike the case of lattice

A review with 49 refs. The dye-sensitized nanocryst. injection solar cell employs transition metal complexes for spectral sensitization of mesoporous TiO2 films together with suitable redox electrolytes or amorphous org. hole conductors. Light harvesting occurs efficiently over the whole visible and near-IR range due to the very large internal surface area of the films. Judicious mol. engineering allows the photoinduced charge sepn. to occur quant. within a few femtoseconds. The certified overall power conv

We investigate the mechanisms leading to the optical non-linearities observed on a strongly excited semiconductor microcavity containing quantum wells. This study of a coupled exciton-cavity system is possible owing to the availability of a sample of exceptionally high quality, permitting to exclude effects of disorder and inhomogeneous broadening. Sub-picosecond pump and probe experiments are performed, in the regime of an incoherent exciton gas of high density. For such a gas the dephasing due to collisio

Photoluminescence intensity and emission wavelength of InAsP/InGaAsP and InGaAs/InGaAsP multi-quantum well (MQW) laser structures grown by chemical beam epitaxy (CBE) at 460 degrees C and V/III ratio of 2 are considerably affected by annealing at temperatures 600-650 degrees C which prevents lasing of these structures fused on GaAs substrates. It is shown that the degradation of luminescence characteristics can be decreased by increasing the growth temperature to 480 degrees C and V/III ratio to 4. InAsP/In

Lattice-matched ZnSe/InxGa1-xAs heterostructures were fabricated by molecular beam epitaxy on GaAs(001)2x4 surfaces. We find that the partial character of the strain relaxation within the ternary layer can be compensated by a suitable excess in the In concentration to match the free-surface lattice parameter to ZnSe. The surface of the II-VI epilayer, however, exhibits a cross-hatched pattern of surface corrugations oriented along orthogonal [110] directions. This complex surface morphology reflects the for

We have recently shown that in II-VI/III-V heterojunctions and related devices fabricated by molecular beam epitaxy, the II/VI flux ratio employed during the early stages of II-VI growth can be used to control the local interface composition and the band alignment. Here we demonstrate that the local interface composition in pseudomorphic, strained ZnSe/GaAs(001) heterostructures as well as lattice-matched ZnSe/In0.04Ga0.96As(001) heterostructures also have a dramatic effect on the nucleation of native stack

We investigated the optical properties of excitons in quasi-one-dimensional semiconductor quantum structures by photoluminescence and photoluminescence excitation: High-quality GaAs/AlxGa1-xAs heterostructures were grown using low-pressure organometallic chemical vapour deposition (OMCVD) on non-planar substrates. The experimentally observed subband separations are in good agreement with a theoretical calculation of the quantum-confined eigenstates, which includes the mapping of the crescent-shaped wire obt

CsI photocathodes were studied in order to evaluate their potential use as large photoconverters in RICH detectors for the PID system at ALICE (LHC in heavy ion collider mode). It has been demonstrated that a quantum efficiency comparable to the reference value obtained on small samples can be obtained on CsI layers evaporated on large pad electrodes operated in a MWPC at atmospheric pressure. We present a survey of the results obtained in the laboratory on small samples irradiated with UV-monochromatic bea

The optical properties of low pressure metal organic vapor deposition grown GaAs/AlxGa1-xAs (x = 0.5) single quantum well structures (SQW) with grown-in dislocations (GD) were studied by low temperature cathodoluminescence (CL) and photoluminescence (PL). High luminescence efficiency around the GD was observed and attributed to impurity decoration. CL spectra show a region surrounding the GD that consists of Si impurities and native defects in the SQW and barrier layers. The diameter of this region was foun

Design and characterization of top-emitting microcavity light-emitting diodes

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Tunable high-efficiency microwave photon detector based on a double quantum dot coupled to a superconducting high-impedance cavity

Modulating non-radiative recombination related to shallow traps in halide perovskites

Theoretical Study of Modified Near-Infrared Light Emission: Quantum Emitters in Plasmonic Nanocavities

Molecular Engineering of Iridium Blue Emitters Using Aryl N-Heterocyclic Carbene Ligands

InGaN/GaN resonant-cavity LED including an AlInN/GaN bragg mirror

High-speed Si resonant cavity enhanced photodetectors and arrays

Space charge and polarization effects upon doping organic light-emitting diodes with pyran-containing donor-acceptor molecules

GaN-based Single Mirror Light Emitting Diodes with high external quantum efficiency

MOLED: simulation of multilayer organic light emitting diodes

Microscopic description of radiative recombinations in InGaN/GaN quantum systems

Ultrafast coherent control of excitons and exciton-polaritons in quantum nanostructure

Separation of strain and quantum-confinement effects in the optical spectra of quantum wires

Molecular Photovoltaics

Intrinsic non-linearities in exciton-cavity-coupled systems

Thermal Stability of InP-Based Structures for Wafer Fused Laser Diodes

Strain and surface morphology in lattice-matched ZnSe/InxGa1-xAs heterostructures

Local interface composition and extended defect density in ZnSe/GaAs(001) and ZnSe/In0.04Ga0.96As(001) heterojunctions

Optical spectroscopy of semiconductor quantum wires

Review of the development of cesium iodide photocathodes for application to large RICH detectors

Cathodoluminescence and Photoluminescence Studies of Dislocations in Gaas/Algaas Quantum-Wells