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Tailoring the confined states for exciton-polaritons in a one-dimensional ZnO microrod
摘要： The application of confinement potential is an efficient way to improve the optical properties of exciton polaritons. In this work, we report experimental studies on the effects of potential landscapes on confined polariton states. The spatial confinement of polaritons was realized by imposing two optically-controlled barriers on a one-dimensional ZnO microrod. Two types of quantized polariton states were observed, where energies of the levels depend either linearly or quadratically on their quantum number. The formation of optical traps with parabolic or square-well profiles was confirmed to be responsible for the observed different states. These results demonstrate the importance of the potential landscapes in tailoring the optical properties of exciton polaritons, which would be helpful in the design of polariton-based optoelectronic devices.
关键词： optoelectronic devices,exciton-polaritons,optical traps,ZnO microrod,confinement potential
更新于2025-09-09 09:28:46
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Ultra-low Noise Balanced Detectors for Optical Time Domain Measurements
摘要： Two ultra-low noise balanced detectors used for optical time domain measurements are presented in this paper. Both simultaneously achieve high bandwidth and low noise that is extremely difficult to realize in commercial detectors. Two-stage amplification circuits based on transimpedance amplifiers (TIAs) were used for these detectors, with special modifications implemented for different applications. To further suppress noise, a low noise junction field effect transistor (JFET) is connected between the photodiode and TIA to reduce the impact of amplifier leakage current in one of the detectors. Benefiting from this design, a 70 MHz sensitive detector with a gain of 3.2E5 V/W and low noise equivalent power density (NEP) of 2.2 pW/rtHz was implemented. For another balanced detector used in higher bandwidth applications, the differential transimpedance amplifier circuit is used, with the detector achieving a 250 MHz bandwidth with a gain of 5E4 V/W, equivalent to NEP of 6.2 pW/rtHz. Due to the difficulty of achieving high bandwidth with low noise, we perform theoretical analysis and simulations for our designs to ensure that these two design goals are realized simultaneously. The performance of the detectors is consistent with our analysis. In addition, a simplified optical testing system was built to test and calculate the performance of the detectors in their respective applications. The results show that both detectors are well balanced and achieve a common mode rejection ratio (CMRR) greater than 50 dB.
关键词： Balanced detectors,optoelectronic devices,time domain measurements,circuit simulations,noise measurements
更新于2025-09-09 09:28:46
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Reference Module in Materials Science and Materials Engineering || SixGe1-x Bulk Crystals
摘要： Germanium–silicon (Ge1(cid:1)xSix) or silicon–germanium (SixGe1(cid:1)x) alloy, where x indicates the mole fraction of silicon, is a complete solid-solution semiconductor having the diamond cubic structure. The lattice parameters of the two elements differ by 4% and those of the solid solution closely follow Vegard's law from 0.564 (pure germanium) to 0.534 nm (pure silicon), while the bandgap changes from 0.72 (germanium) to 1.2 eV (silicon) according to composition. GeSi alloys are important for both microelectronic and optoelectronic devices and various functional materials because of the potential for bandgap and lattice parameter engineering they offer. The phase diagram of GeSi alloy is shown in Figure 1. The solidus and liquidus curves are widely separated. The equilibrium distribution coef?cient, k0 ? xs/xl (xs and xl being the solidus and liquidus concentration of silicon), is as large as 6 for germanium-rich solutions and about 2.2 at the average melting-point temperature of each element. Such a large gap between the liquidus and the solidus and the difference in the physical properties of the constituent elements, such as density, lattice parameter, and melting temperature, make the crystal growth of GeSi alloys very dif?cult. This article provides an outline of the applications and reviews the growth of bulk GeSi, discussing relevant problems, residual defects, impurities and dopants, and covers the structural properties of the alloys. The study of such alloys is also of interest from the fundamental view point of solidi?cation.
关键词： solid-solution semiconductor,crystal growth,microelectronic devices,optoelectronic devices,GeSi alloys
更新于2025-09-04 15:30:14
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Reduced Graphene Oxide Nanostructures by Light: Going Beyond the Diffraction Limit
摘要： Graphene oxide (GO) offers excellent possibilities that are recently demonstrated in many applications ranging from biological sensors to optoelectronic devices. The process of thermal annealing aids in removing the oxygen-containing groups in GO, making GO more graphene-like, or the so-called reduced graphene oxide (rGO). Thermal reduction can also be achieved by intense light. Here, we demonstrate a scalable, inexpensive, and environmentally friendly method to pattern graphene oxide films beyond the diffraction limit of light using a conventional laser. We show that contrary to previous reports, non-linear effects that occur under high intensity conditions of laser irradiation allow the fabrication of highly conductive carbon nanowires with dimensions much smaller than the laser spot size. The potential of this method is illustrated by the fabrication of several devices on flexible and transparent substrates, including hybrid plasmonic/rGO sensors.
关键词： reduced graphene oxide,optoelectronic devices,laser reduction,Graphene oxide,diffraction limit
更新于2025-09-04 15:30:14
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Enhanced Temperature-Tunable Narrow-Band Photoluminescence from Resonant Perovskite Nanograting
摘要： Tunable light-emitting nanostructures are prospective for reconfigurable compact optoelectronic devices. In this regard, halide perovskites are one of the most efficient class of materials, because of their outstanding electronic and optical properties as well as low cost of fabrication and nanostructuring. Here, we study the temperature-tunable reconfiguration of photonic modes in periodically nanostructured perovskite (MAPbI3) film probed by enhanced photoluminescence. We achieved the quality factors of resonances around 500 at wavelengths 750–760 nm. The experimental results are in well agreement with theoretical simulations. Our study reveals the origin of the emission enhancement from such kind of perovskite nanostructures and paves the way to highly directional, efficient, and tunable narrowband emission from optoelectronic devices.
关键词： Optoelectronic devices,Photoluminescence,Tunable light-emitting nanostructures,Halide perovskites,Nanogratings
更新于2025-09-04 15:30:14
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Synthesis, Photophysical, Electrochemical and Thermal Study of Biphenyl Luminophors: Green Light Emitting Materials
摘要： Novel luminophors of anthracene (AN) and tetracene (TN) doped biphenyl were prepared using Conventional Solid State reaction technique. Fluorescence spectroscopy, XRD, SEM, TGA-DSC and Cyclic Voltammetry techniques have been employed for photophysical, electrochemical and thermal study. The X-ray diffraction study revealed the formation of homogeneous biphenyl solid solutions with the added guests AN and TN. Fluorescent biphenyl absorbing short wave UV radiation and emitting at long wave UV radiation has been used as a solid matrix. From the fluorescence spectra it is seen that the added guests shifts the UV fluorescence of biphenyl emitting in green region of visible spectrum at 532 nm. SEM images of the prepared luminophors showed the crystallites of average size 140 nm which makes them suitable candidates for their use in Optoelectronic devices. HOMO and LUMO energy levels of the synthesized luminophors from electrochemical data observed in 5.50–5.64 eV and 3.09–3.13 eV with band gap 2.37–2.55 eV, respectively. TGA-DSC study revealed the thermal stability of prepared luminophors.
关键词： Green light emitting novel luminophors,EET process,Optoelectronic devices
更新于2025-09-04 15:30:14
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Phosphomolybdic acid as an efficient hole injection material in perovskite optoelectronic devices
摘要： Efficient perovskite devices consist of a perovskite film sandwiched between charge selective layers, in order to avoid non-radiative recombination. A common metal oxide used as a p-type or hole transport layer is molybdenum oxide. MoO3 is of particular interest for its very large work function, which allows it to be used both as an interfacial charge transfer material and a dopant for organic semiconductors. However, high quality and high work function MoO3 is typically thermally evaporated in a vacuum. An alternative solution-processable high work function material is phosphomolybdic acid (PMA), which is stable, commercially available and environmentally friendly. In this Communication, we show the first application of PMA in efficient vacuum processed perovskite devices. We found that the direct growth of perovskite films onto PMA leads to strong charge carrier recombination, hindering the solar cell photovoltage. Using an energetically suitable selective transport layer placed between PMA and the perovskite film, solar cells with efficiency >13% as well as LEDs with promising quantum efficiency can be obtained.
关键词： LEDs,optoelectronic devices,perovskite,hole injection material,phosphomolybdic acid,solar cells
更新于2025-09-04 15:30:14