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Power- and Spectral-Dependent Photon-Recycling Effects in a Double-Junction Gallium Arsenide Photodiode
摘要： Photon recycling effects improve radiative efficiencies of semiconductor materials, and play important roles in the design of high performance optoelectronic devices. Conventional research mostly studies the impact of photon recycling on the voltage of photodiodes. Here we systematically analyze the photon response of a microscale gallium arsenide (GaAs) based double junction photodiode. In such a device, the current matching condition between two subcells is determined by their photon coupling. Photodynamics in the device is examined and reveals the material’s internal quantum efficiencies. By leveraging photon distributions inside the device, we discover that its photocurrent and spectral responses are highly dependent on the illumination intensity. Consistent with theoretical analyses, the device’s photocurrents exhibit linear and superlinear power dependent characteristics under near-infrared and violet-blue illuminations, respectively. Due to strongly enhanced photon recycling effects under strong illumination, broadband photon responses (external quantum efficiency close to 50% from 400 nm to 800 nm) could be achieved in such a strongly current mismatched GaAs dual junction device. The understanding of photon processes in such devices would offer routes to the design of high-performance photodetectors and solar cells.
关键词： photovoltaics,photodetectors,gallium arsenide,photon recycling,multijunction
更新于2025-09-23 15:23:52
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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) - Demonstrating the GaInP/GaAs Three-Terminal Heterojunction Bipolar Transistor Solar Cell
摘要： The three-terminal heterojunction bipolar transistor solar cell (HBTSC) concept enables the realization of a monolithic double-junction device with individual current extraction. We present an HBTSC realized by a heterojunction of GaInP and GaAs. The one-sun open-circuit voltage (VOC ) of the top and bottom junctions are 1.33 V and 0.99 V, respectively, while ?ll factors (FF) are above 80%. At one-sun illumination, reducing one junction’s bias from VOC to maximum power point degrades the performance of the other junction only slightly (< 0.5% ef?ciency loss). These results demonstrate the potential of the HBTSC concept to produce high-ef?ciency independently connected double-junction solar cells.
关键词： photovoltaic cells,independent current,multi terminal,gallium indium phosphide,gallium arsenide,double junction
更新于2025-09-23 15:21:01
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[IEEE 2018 IEEE 5G World Forum (5GWF) - Silicon Valley, CA, USA (2018.7.9-2018.7.11)] 2018 IEEE 5G World Forum (5GWF) - Packaged High Power Frond-End Module for Broadband 24GHz & 28GHz 5G solutions
摘要： This paper presents realization and characteristics of broadband plastic low cost packaged 5G High Power Frond-End (HPFE) operating in 24-31GHz bandwidth. This demonstrator includes a Transmit and Receive paths realized on mixed technologies: 150nm Gallium Nitride on Silicon Carbide (AlGaN/GaN on SiC) and 150nm Gallium Arsenide (GaAs). Continuous Wave (CW) measured power results of the Transmit path (Tx) demonstrates a maximum output power (POUT,Tx) higher than 2W (33.5dBm) with 25% drain efficiency (DE), 24% power added efficiency (PAE), and 36dB of insertion gain (GI,Tx) in the 24-31GHz bandwidth. The receiver path (Rx) presents an maximum output power (POUT,Rx) of 30mW (15.5dBm) and an average Noise Figure (NF) of 3.6dB with an associated Insertion Gain (GI,Rx) of 20dB in the same bandwidth. The HPFE/Tx linearity has been investigated with several M-QAM modulation signals with 25/50 and 100MHz channel spacing and using Digital Pre-Distortion (DPD) leading to 48dBc Adjacent Channel Leakage Ratio (ACLR) and 40dB Mean Squared Error (MSE) for average output powers ranging from linearity performances have been 17dBm to 25dBm. The compared to the ones obtained with two other linear GaAs amplifiers to point telecommunications application: the HPFE presents similar linearity performances associated to a higher efficiency. Thanks to the mixed technologies approach, an optimized trade-off in terms of integration, electrical performances and cost has been demonstrated.
关键词： MMIC,PHEMT,Gallium Arsenide,Plastic packaging,Transmit/Receive path,Low Noise Amplifier,Gallium Nitride,Power Amplifier,Switch
更新于2025-09-23 15:21:01
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Photovoltaic anodes for enhanced thermionic energy conversion
摘要： Thermionic energy converters are heat engines based on the direct emission of electrons from a hot cathode towards a colder anode. Since the thermionic emission is unavoidably accompanied by photonic emission, radiative energy transfer is a significant source of losses in these devices. In this letter, we provide the experimental demonstration of a hybrid thermionic-photovoltaic device that is able to produce electricity not only from the electrons, but also from the photons that are emitted by the cathode. Thermionic electrons are injected in the valence band of a gallium arsenide semiconducting anode, then pumped to the conduction band by the photovoltaic effect, and finally extracted from the conduction band to produce useful energy before they are re-injected in the cathode. We show that such a hybrid device produces a voltage boost of ~ 1V with respect to a reference thermionic device made of the same materials and operating under the same conditions. This proof of concept paves the way to the development of efficient thermionic and photovoltaic devices for the direct conversion of heat into electricity.
关键词： thermionic energy conversion,photovoltaic,hybrid device,voltage boost,gallium arsenide
更新于2025-09-23 15:21:01
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Gallium arsenide waveguides as a platform for direct mid-infrared vibrational spectroscopy
摘要： During recent years, mid-infrared (MIR) spectroscopy has matured into a versatile and powerful sensing tool for a wide variety of analytical sensing tasks. Attenuated total reflection (ATR) techniques have gained increased interest due to their potential to perform non-destructive sensing tasks close to real time. In ATR, the essential component is the sampling interface, i.e., the ATR waveguide and its material properties interfacing the sample with the evanescent field ensuring efficient photon-molecule interaction. Gallium arsenide (GaAs) is a versatile alternative material vs. commonly used ATR waveguide materials including but not limited to silicon, zinc selenide, and diamond. GaAs-based internal reflection elements (IREs) are a new generation of semiconductor-based waveguides and are herein used for the first time in direct spectroscopic applications combined with conventional Fourier transform infrared (FT-IR) spectroscopy. Next to the characterization of the ATR waveguide, exemplary surface reactions were monitored, and trace-level analyte detection via signal amplification taking advantage of surface-enhanced infrared absorption (SEIRA) effects was demonstrated. As an example of real-world relevance, the mycotoxin aflatoxin B1 (AFB1) was used as a model analyte in food and feed safety analysis.
关键词： Mid-infrared chem/biosensor,Surface modification,Gallium arsenide,Self-assembled monolayers,Evanescent field absorption,Surface-enhanced infrared absorption
更新于2025-09-23 15:21:01
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Evaluation of GaAs solar cells grown under different conditions via hydride vapor phase epitaxy
摘要： In this study, we characterize the GaAs solar cells grown under di?erent conditions using a custom-built at-mospheric-pressure hydride vapor-phase epitaxy (HVPE) reactor. Under typical HVPE growth involving the decomposition of AsH3 to Asx, the growth rate is considerably dependent on the temperature and is limited to ~10 μm/h at a low deposition temperature of 660 °C because of the large kinetic barrier of 198 kJ/mol. Herein, we grow GaAs with a considerably lower kinetic barrier of 7 kJ/mol by suppressing the decomposition of AsH3 in the reactor. Further, we grew GaAs solar cells at an extremely high growth rate of 120 μm/h using uncracked AsH3. However, the open-circuit voltage (VOC) was reduced from 1.0 V for the cells grown at 8 μm/h under typical growth using Asx to 0.95 V for the cells grown at 120 μm/h using hydride-enhanced growth. The reduction in VOC was attributed to the modulation of both the doping pro?le and the abruptness of hetero-interfaces. A small amount of residual gases, which presents at the growth surface after the growth of the p-InGaP back surface ?eld layer, is prominently incorporated during the growth of the p-GaAs base layer upon hydride-enhanced growth due to the fast kinetics.
关键词： B3. Solar cells,A3. Hydride vapor phase epitaxy,B2. Semiconducting gallium arsenide,B1. Alloys
更新于2025-09-23 15:19:57
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Radiation-resistant solar cells for space
摘要： Solar cells made with nanowires can tolerate up to 40 times as much high-energy radiation as those made of flat crystalline films, making the nano versions well suited for powering satellites and spacecraft. Harry A. Atwater of the California Institute of Technology and colleagues fabricated solar cells with a light-absorbing layer made of an array of either 3 μm long gallium arsenide or 2 μm long indium phosphide nanowires grown vertically from the substrate. The researchers irradiated the devices with protons at 100 and 350 keV, comparable to what they would experience in space. Compared with thin-film solar cells made from the same materials, the nanowire solar cells withstood 10–40 times as many protons before their current degraded. Simulations showed that energetic protons shoot out of nanowires, minimizing damage, while they lodge in crystalline films. The researchers think that the higher surface area of the nanowires makes it easier for defects to migrate out of the structures.
关键词： solar cells,space,indium phosphide,radiation-resistant,nanowires,gallium arsenide
更新于2025-09-23 15:19:57
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Numerical optimisation and recombination effects on the vertical-tunnel-junction (VTJ) GaAs solar cell up to 10,000 suns
摘要： Ultra-high concentrator photovoltaic systems (UHCPV), usually referred to CPV systems exceeding 1000 suns, are signalled as one of the most promising research avenues to produce a new generation of high-efficiency and low-cost CPV systems. However, the structure of current concentrator solar cells prevents their development due to the unavoidable series resistance losses at such elevated concentration ratios. In this work, we investigate the performance of the so-called vertical-tunnel-junction (VTJ), recently introduced by the authors, by using advance TCAD. In particular, we carry out an optimisation procedure of the key parameters that affect its performance and conduct a deep investigation of the impact of the main recombination mechanisms and of sun concentration up to 10,000 suns. The results indicate that the performance of the novel structure is not significantly affected by these two factors. A record efficiency of 32.2% at 10,000 suns has been found. This represents a promising way to obtain state-of-the-art efficiencies above 30% for single-band-gap cells, and offers a new route towards the development of competitive CPV systems operating at ultra-high concentration fluxes.
关键词： Tunnel diode,Concentrator photovoltaics,Vertical solar cells,Series resistance,Gallium arsenide (GaAs)
更新于2025-09-23 15:19:57
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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) - Reciprocal relationship between photoluminescence and photocurrent in two-step photon up-conversion solar cell
摘要： Two-step photon up-conversion solar cell (TPU-SC) we have recently proposed is a single-junction solar cell containing a hetero-interface of different semiconductor materials. Although efficient two-step photon up-conversion is achieved in the TPU-SC, the detailed mechanism of intraband photoexcitation occurring at the hetero-interface is still unclear. In this study, we performed simultaneous measurements of photoluminescence and photocurrent as a function of the applying bias voltage in the TPU-SC. We experimentally demonstrate the reciprocity relationship between the radiative recombination and the photocurrent of the TPU-SC.
关键词： photovoltaic cells,gallium arsenide,quantum dots,heterojunctions,radiative recombination,photoluminescence
更新于2025-09-23 15:19:57
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Performance analysis of GaAs based solar cells under gamma irradiation
摘要： The influence of gamma irradiation on gallium arsenide based photovoltaic cells was investigated. This type of solar cell is used for advanced space application where radiation degradation occurs in particular. A synthetic radioactive isotope of cobalt Co-60 was used with an applied dose of up to 500 kGy. These irradiation cause damage and degradation of the solar cell. A wide range of comparative characterisation methods was performed before and after irradiation. The effect of radiation on material morphology was described using electron and atomic force microscopy. Structural changes were investigated by Secondary Ion Mass Spectrometry (SIMS) with Time-of-Flight mass analysis (TOF) and Raman spectroscopy analysis. Also, the changes in noise fluctuations and current-voltage characteristics of the cell in the dark and under illumination were measured. Based on experimental measurements, the degradation was observed in the structural, optical and material cell properties as well as in electrical parameters.
关键词： Radiation,Solar cells,Gallium arsenide,Cobalt-60,Degradation
更新于2025-09-23 15:19:57