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- differential low noise amplifier
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Outdoor Performance of PV Technologies in Simulated Automotive Environments
摘要： GaAs, monocrystalline Si, and multicrystalline Si modules were tested in a configuration designed to simulate car-roof-integrated mounting. The increase in module temperature above ambient was similar for the four Si modules, but less (~76%) for the GaAs modules. Local temperatures within each module were strongly dependent on the optical properties of the back sheet. The lower operating temperature combined with smaller temperature coefficient of the GaAs modules resulted in higher performance ratios for the GaAs modules even for ambient temperature < 25°C. The quantification of the relative performance of the modules in a thermal environment relevant to implementation in vehicles provides information for the selection of PV modules for this emerging application.
关键词： monocrystalline Si,GaAs,performance ratios,module temperature,automotive environments,multicrystalline Si,PV technologies
更新于2025-09-19 17:13:59
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Minimal Magnetic Dipole Moment for the Solar Cell Array Using GaInP/GaAs/Ge Cells
摘要： The only ambient power source in space is solar energy, which is harvested by photovoltaic conversion with solar cells. Since about 20 years ago, silicon solar cells have been used extensively as the primary power devices in space. However, in recent years, GaInP/GaAs/Ge solar cells with triple junction technology, have been widely used as power-generation devices for space applications. Not only do the GaInP/GaAs/Ge solar cells have better conversion efficiency compared to Si solar cells, but it is also possible to supply the required electric power using a smaller number of solar cells. While there are advantages when using the GaInP/GaAs/Ge solar cells, methods for design of systems of strings should be established for minimizing their magnetic dipole moment. This is because the voltage and current are three times greater than with Si solar cells, and this must be considered. By electromagnetic theory, loop current of a string consisting of cells in series occurs when flowing through it. That magnetic dipole moment can affect attitude control when using magnetic torque bars in orbit, and spacecraft systems require no more than 0.25 Am2 of magnetic dipole moment for optimal attitude control. Therefore, we designed a single string of GaInP/GaAs/Ge solar cells and tested its current capacity to see and minimize the magnetic dipole moment. Finally, we proposed an optimal string design methodology by a test coupon solar cell array using GaInP/GaAs/Ge solar cells by simulation and implemented it on a substrate of carbon fiber reinforced plastic material to see how well the prototype worked or did not work. In future, the string design methodology could be extended to a larger solar cell array by using this coupon design methodology to minimize the magnetic dipole moment.
关键词： Carbon fiber reinforced plastics,GaInP/GaAs/Ge,Solar cell,String,Magnetic dipole moment
更新于2025-09-19 17:13:59
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Temperature effect on the binding energy and the diamagnetic susceptibility of a magneto-donor in Cylindrical Quantum Dot (GaAs/GaAlAs)
摘要： In this work, the effect of the temperature on the binding energy and the diamagnetic susceptibility of a shallow magneto-donor confined to move in a cylindrical quantum dot made out of GaAs/GaAlAs is studied within the effective mass approximation. We describe the quantum confinement by an infinite deep potential. The results show that when the temperature or the magnetic field increases, (i) the binding energy increases and (ii) the absolute value of the diamagnetic susceptibility decreases. Its effects depend strongly on the size of the CQD.
关键词： GaAs/GaAlAs,temperature effect,binding energy,cylindrical quantum dot,diamagnetic susceptibility,magneto-donor
更新于2025-09-19 17:13:59
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Time-resolved measurements of two-color laser light emitted from GaAs/AlGaAs-coupled multilayer cavity
摘要： We measured the two-color laser oscillation from a GaAs/AlGaAs-coupled multilayer cavity at 18 °C–42 °C using current injection. We confirmed simultaneous lasing by detecting the sum frequency generation signal generated by the two-color laser light, and performed time-resolved measurement using a streak camera with a spectrometer. From the observed time transient of the spectra at various temperatures, it is clarified that the temperature change of the device, induced by current injection, modulates the effective cavity length. Therefore, the temperature control of the device is a key factor in stable two-color lasing and THz wave generation.
关键词： time-resolved measurements,sum frequency generation,THz wave generation,GaAs/AlGaAs-coupled multilayer cavity,two-color laser
更新于2025-09-19 17:13:59
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Electric bias-controlled switching of magnetization of ferrimagnetically coupled Mn delta-layers in a GaAs-AlGaAs quantum well
摘要： We suggest a model of synthetic ferrimagnetic semiconductor structure based on GaAs-AlGaAs quantum well doped by two Mn delta-layers. The coupling between the delta-layers is mediated by extra holes, and can be switched between ferro- and antiferromagnetic one by gating the structure. A proper choice of Mn concentrations in the delta-layers and of local degree of disorder enables fabrication of a ferrimagnetic structure supporting ultrafast switching of magnetization by short pulses of electric bias without an external magnetic field. The switching mechanism in the structure relies on kinetic spin exchange between the two delta-layers which is mediated by exchange scattering of electric-pulse heated holes by magnetic ions within the layers. Owing to specific interplay between characteristics of the exchange scattering, spin decay times, and the heat withdraw in the suggested synthetic ferrimagnetic semiconductor, the necessary parameters of electric-bias pulse are within the technologically accessible range, and do not contradict typical thermal kinetics of semiconductor structures.
关键词： ultrafast heating,GaAs quantum well,synthetic ferrimagnet,ultrafast switching of magnetization
更新于2025-09-19 17:13:59
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Evolution of InAs quantum dots and wetting layer on GaAs (001): Peculiar photoluminescence near onset of quantum dot formation
摘要： InAs quantum dots (QDs) have been grown on a GaAs (001) substrate in the subcritical region of InAs coverage for transition from a 2-dimensional (2D) to a 3-dimensional growth mode. Evolution of QDs and the corresponding wetting layer (WL) with InAs coverage has been investigated. Under specific growth conditions, quantum dot formation was observed only in samples where InAs coverage is more than 1.48 ML. The QD density increases sharply with InAs deposition initially but slows down with increased coverage. Photoluminescence (PL) shows the existence of a third peak, other than QD and WL peaks, at the low energy side of the WL peak, which is named the precursor peak. Evidence is presented supporting the theory that this peak is due to 2D InAs islands on a monolayer of InAs, which are small enough to localize excitons. Meanwhile, the WL peak is due to larger InAs islands under high compressive strain. During QD formation, the WL peak energy increases with the increase in InAs deposition. This is due to the sudden transfer of material from the bigger size of InAs islands to the QD. Our results show that the QD, WL, and precursor peaks coexist near the onset of QD formation. The power dependence of the three PL peaks is evident, which supports to our conclusion.
关键词： precursor peak,InAs quantum dots,wetting layer,photoluminescence,GaAs substrate
更新于2025-09-19 17:13:59
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Investigation of the incident light intensity effect on the internal electric fields of GaAs single junction solar cell using bright electroreflectance spectroscopy
摘要： The incident light intensity (Iex) effects on a GaAs single junction solar cell (SC) was investigated using bright electroreflectance spectroscopy (BER) and current-voltage (J-V) measurements at room temperature. The p-n junction electric field (Fpn) of the SC was evaluated by analyzing the Franz Keyldesh oscillation (FKO) in the BER spectra. The Iex effect on Fpn was investigated at various incident light intensities from 0.03 to 25 suns. The Fpn decreased gradually with increasing Iex due to the photovoltaic effect. For the forward bias voltage, some part of the electrons and holes drifted to the p and n sides, respectively, and produced the induced electric field in the same direction of the Fpn. Therefore, the Fpn increased up to 2.5 suns. At more than 2.5 suns, most of the electrons and holes moved to the n and p sides and decreased the Fpn due to the photovoltaic effect. In addition, the Fpn was examined under light illumination as a function of different DC bias voltages (-0.2 ~ 0.4 V). The Fpn decreased with increasing bias voltage due to the decrease in potential barrier. The Fpn increased with increasing bias voltage due to the decrease in the photogenerated carrier-induced electric field for high Iex.
关键词： GaAs solar cell,Bright electroreflectance spectroscopy,Electric field
更新于2025-09-19 17:13:59
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MBE growth of InAs/GaAs quantum dots on sintered porous silicon substrates with high optical quality??in the 1.3 ??m band
摘要： We report self-assembled InAs/GaAs quantum dots (QDs) monolithically grown on a compliant transferable silicon nanomembrane. The transferable silicon nanomembrane with flat continuous crystalline silicon layer formed via in situ porous silicon sintering is considered a low-cost seed for heteroepitaxy of free-standing single-crystalline foils for photovoltaic cells. In this paper, the compliant feature of transferable silicon nanomembrane has been exploited for direct growth of high-quality InAs/GaAs (QDs) by molecular beam epitaxy. Bright 1.3 μm room temperature photoluminescence from InAs/GaAs QDs has been obtained. The excellent structural and optical qualities of the obtained InAs/GaAs quantum dots offer great opportunities for realizing a low-cost and large-scale integration of III–V-based optoelectronic device on silicon.
关键词： optoelectronic devices,InAs/GaAs quantum dots,molecular beam epitaxy,sintered porous silicon,photoluminescence
更新于2025-09-19 17:13:59
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Optical simulation and geometrical optimization of P3HT/GaAs nanowire hybrid solar cells for maximal photocurrent generation via enhanced light absorption
摘要： The implications of using the combination of inorganic and organic materials in the active layer of solar cells have motivated researchers to find a new pathway for flexible, low cost, and highly efficient future generation solar cells. III-V material based nanowires (NWs) with subwavelength scale diameters have shown excellent light harvesting and charge transport properties and can be easily combined with organic polymer materials and thin substrates to design hybrid solar cells (HSCs). To obtain optimum design requirements for GaAs nanowire array (NWA) HSCs, an optical simulation of poly(3-hexylthiophene) P3HT/ GaAs (NWA) hybrid solar cell is investigated using finite-difference-time-domain (FDTD) method. In comparison to planar substrate, P3HT coated NWA have shown superior optical properties owing to its intrinsic anti-reflection, broad absorption spectra, and efficient excitation of resonance modes. A steady improvement in light absorption of P3HT/GaAs NWA HSCs is observed as the polymer coating thickness increased up to a certain limit and beyond which there is a significant degradation in the exciton generation. The geometrical parameters like diameter (D) of NW and filling ratio or periodicity are also optimized to achieve superior light absorption and maximum short circuit current density (Jsc). Under AM1.5G illumination, maximum photocurrent obtained for optimized structure with conformal coating of P3HT is almost 12% and 15% higher than its fully infiltrated and uncoated counterparts respectively.
关键词： Hybrid solar cells,FDTD,GaAs NWs,P3HT,Absorption
更新于2025-09-16 10:30:52
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[IEEE 2019 TEQIP III Sponsored International Conference on Microwave Integrated Circuits, Photonics and Wireless Networks (IMICPW) - Tiruchirappalli, India (2019.5.22-2019.5.24)] 2019 TEQIP III Sponsored International Conference on Microwave Integrated Circuits, Photonics and Wireless Networks (IMICPW) - Design of GaAs-Photonic Crystal Based Polarization Splitter
摘要： Photonic Crystal has attracted many researchers because of their distinctive capabilities, larger application areas. In this paper, a polarization splitter based on photonic crystal is developed with the help of photonic band gap diagram and self-collimation method. The photonic crystal based splitter is constructed in hexagonal lattice structure with GaAs rods placed in air. To obtain the band diagram, the radius of the rods is considered as 100 nm with lattice constant of 500nm. The developed polarization splitter is simulated using RSOFT software. It is observed through the simulation results that Cthe proposed splitter design achieves better transmission spectral and optical field distributions for both TE and TM modes. Power dissipation is reduced compared to that of existing splitters. 90% transmission is obtained for the proposed model.
关键词： Polarization splitter,Photonic crystals,GaAs
更新于2025-09-16 10:30:52