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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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Numerical Simulation of GaAs Solar Cell Aging Under Electron and Proton Irradiation
摘要： Though gallium arsenide (GaAs) solar cells are proven to be relatively stable in space working conditions, they are prone to the effects of aging, which deteriorate their characteristics. The lifetime of solar cells is restricted by the degree of radiation damage that they receive. This important factor affects the performance of solar cells in practical applications. The aim of this article is to investigate by numerical simulation on the influence of aging on the main characteristics of GaAs solar cells in the space. Degradations of the electrical characteristics are simulated for over a period of 15 years. The atmosphere (AM0) conversion efficiency decreases with time from 19.08% for the unirradiated cells to 10.38% in 15 years of the mission in space. Even with low doses of particle irradiation, the performance is significantly reduced subsequent to usage over the period of 15 years of the mission in space. Numerical simulation results also reveal that the short-circuit current, the open-circuit voltage, and the conversion efficiency decline gradually with time. Moreover, the calculated evolutions are in good agreement with the measured behaviors of GaAs-based solar cells embedded in geostationary satellites during the Navigation Technology Satellite 2 (NTS-2), the Engineering Test Satellite V (ETS-V), and the NAVigation Satellite Timing And Ranging (NAVSTAR) missions, which substantiate the introduced aging law accounting for both the cumulated doses of particles and the different electron and hole traps in the structure.
关键词： space application,model,Degradation,gallium arsenide (GaAs) solar cell
更新于2025-09-12 10:27:22
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Accurate and efficient analysis of the upward heat flow in InGaP/GaAs HBTs through an automated FEM-based tool and Design of Experiments
摘要： This paper presents an extensive analysis aimed at quantifying the impact of all the key technology parameters on the upward heat flow in state‐of‐the‐art InGaP/GaAs heterojunction bipolar transistors (HBTs) for various emitter areas and shapes. Extremely accurate thermal simulations are conducted in a relatively short time with a tool relying on a commercial 3‐D finite‐element method (FEM) solver and an in‐house routine for automated geometry construction, optimized mesh generation, sequential solution, and data storing/processing. Design of Experiments is used to define a thermal resistance model as a function of the aforementioned parameters on the basis of a few FEM data.
关键词： finite‐element method (FEM),gallium arsenide (GaAs),Design of Experiments (DOE),thermal simulation,thermal resistance,heterojunction bipolar transistor (HBT)
更新于2025-09-04 15:30:14
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A Compact Ka-Band Integrated Doherty Amplifier With Reconfigurable Input Network
摘要： In this paper, we present the design of an ultracompact monolithic millimeter-wave integrated circuit Doherty power amplifier (DPA) using a novel reconfigurable input network at Ka-band. The proposed input network is formed by a compact broadside coupler and two additional field-effect transistors. By reconfiguring the relative phase offset between the main and auxiliary amplifiers, the DPA can be postoptimized to achieve high efficiency and maximal power gain flatness. More importantly, the DPA can be tuned for the highest performance at different frequencies. To verify the concept, a DPA is fabricated in a 0.15-μm enhancement mode Gallium Arsenide (GaAs) process and exhibits a measured output power of 26.5 dBm and gain of 11.8 dB at 28 GHz. The peak power-added efficiency (PAE) is 42%, and the PAE at 6-dB output power backoff (PBO) is 31%, respectively. With reconfigurable capability, the DPA can maintain high performance over a 3-GHz frequency band from 26.5 to 29.5 GHz. To the best of the authors’ knowledge, the proposed DPA achieves among the highest backoff PAE over a wide bandwidth at Ka-band.
关键词： reconfigurable,Ka-band,gallium arsenide (GaAs),Doherty power amplifier (DPA),millimeter-wave integrated circuit (MMIC),Compact coupler
更新于2025-09-04 15:30:14
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Micro-fabricated wideband band-stop filter using GaAs-based integrated passive device technology
摘要： This paper presents a new concept of implementing a micro-fabricated wideband band-stop filter on a gallium arsenide (GaAs) substrate using integrated passive device technology. The incorporation of an air-bridge structure was explored to enhance design flexibility and achieve excellent radio-frequency performance of the filter. A wideband band-stop filter was realized on a GaAs substrate, generating an insertion loss of ? 0.37 dB and a return loss of ? 38 dB with excellent attenuation of ? 28.78 and ? 22.27 dB, in the lower and the upper passband, respectively. The filter resonates at 10.72 GHz, occupying a die area of 2000 μm × 1540 μm. The selectivity of the filter is reflected by its tremendous suppression of out-of-band signals with the existence of attenuation poles in the vicinity of the resonance frequency. Experimental verification of the filter response demonstrates its potential use as an on-chip device operating in the X-band frequency spectrum.
关键词： Gallium arsenide (GaAs),Wideband band-stop filter,Radio frequency (RF),Integrated passive device technology,Micro-fabrication
更新于2025-09-04 15:30:14
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Research on Time Jitter of GaAs Photoconductive Semiconductor Switches in the Negative Differential Mobility Region
摘要： Time jitter of GaAs photoconductive semiconductor switches (PCSS) is investigated at an optical excitation of 1053 nm wavelength and 500 ps pulse duration. The experimental results indicate that the time jitter of the GaAs PCSS exhibits a nonmonotonic variation in negative differential mobility (NDM) region. All of these time jitters are lower than the 4% of the rise time of the switching waveform. The optimum time jitter of ~15 ps is achieved at the onset of the NDM region. The theoretical relationship between the optical excitation parameters, the bias electric field and the time jitter of the GaAs PCSS are built up. The nonmonotonic behavior of the time jitter with electric field is attributed to the instability of the relative fluctuation of drift velocity caused by inter-valley transition of carriers in GaAs.
关键词： inter-valley transition of carriers,photoconductive semiconductor switches,gallium arsenide (GaAs),negative differential mobility (NDM),time jitter
更新于2025-09-04 15:30:14