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Development and Analysis of Wafer-Bonded Four-Junction Solar Cells Based on Antimonides With 42% Efficiency Under Concentration
摘要： The highest solar cell efficiencies today are reached with four-junction devices under concentrated illumination. The optimal bandgap combination for realistic four-junction cells is modelled to be 1.89/1.42/1.05/0.68 eV and indeed promises for efficiencies >50%. We present the development and analysis of a wafer-bonded four-junction solar cell based on GaInP/GaAs/GaInAs//GaInAsSb. This concept allows for the implementation of these ideal bandgaps and exhibits at present an efficiency of 42.0±2.5% at a concentration of 599x AM1.5d. The present loss mechanisms in this device are analyzed, which are dominated by current losses due to mismatched subcell currents and absorbing passive layers. Under the assumption of proper current matching, this device would achieve an efficiency above 44%.
关键词： metal-organic vapour phase epitaxy (MOVPE),multijunction solar cells,wafer bonding,Antimonides,four-junction solar cells
更新于2025-09-16 10:30:52
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Molecular beam epitaxy growth and characterization of interband cascade infrared detectors on GaAs substrates
摘要： Interband cascade infrared detectors (IB CIDs) are devices built from multiple cells connected in series using specially designed interband tunneling and relaxation regions. Such design enables effective collection of photogenerated carriers and is particularly beneficial in the case of short diffusion length in absorber’s material. In this work, we report on the growth and characterization of type-II InAs/GaSb superlattices IB CIDs on highly lattice-mismatched (001) GaAs substrates for mid-wave range. IB CIDs are characterized by high resolution X-ray diffraction, dark current and current responsivity. The performance of devices with different number of stages is discussed. Devices with 50% cut-off wavelength at 5.3 μm exhibit at temperature 300 K peak detectivity of 3.6×108 cmHz1/2W-1.
关键词： B1. Gallium arsenide substrate,A3. Molecular beam epitaxy,B1. Antimonides,B3. Infrared devices
更新于2025-09-16 10:30:52
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Room-temperature photoluminescence of AP-MOVPE grown single GaSb/GaAs quantum dot layer
摘要： The effect of GaAs host matrix on excitonic behaviour in AP-MOVPE grown GaSb/GaAs quantum dots (QDs) was investigated. Room temperature (RT) photoluminescence (PL) emission was achieved from single layers of quantum dots by controlling the GaAs host matrix growth temperature. Samples were prepared using a GaSb dot growth temperature of 530 °C, followed by growth of a thin GaAs ‘cold’ cap, before depositing the final part of the GaAs capping layer at either 550 °C, 600 °C or 650 °C. PL measurements at 10 K revealed QD emission peaks for all the samples at around 1.1 eV. However, variable temperature PL revealed different thermal quenching rates of the emission, with the rates of quenching reduced with increasing GaAs growth temperature. This was ascribed to reduced defect densities in GaAs grown at higher temperature, which resulted in QD emission even at RT. The hole localisation energy determined for these samples at RT was approximately 470 meV.
关键词： Defects,Antimonides,Metalorganic vapor phase epitaxy,Nanostructures,Gallium compounds
更新于2025-09-12 10:27:22
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First-principles many-body study of the electronic and optical properties of CsK <sub/>2</sub> Sb, a semiconducting material for ultra-bright electron sources
摘要： We present a comprehensive first-principles investigation of the electronic and optical properties of CsK2Sb, a semiconducting material for ultra-bright electron sources for particle accelerators. Our study, based on density-functional theory and many-body perturbation theory, provides all the ingredients to model the emission of this material as a photocathode, including band gap, band dispersion, and optical absorption. An accurate description of these properties beyond the mean-field picture is relevant to take into account many-body effects. We discuss our results in the context of state-of-the-art electron sources for particle accelerators to set the stage towards improved modeling of quantum efficiency, intrinsic emittance, and other relevant quantities determining the macroscopic characteristics of photocathodes for ultra-bright beams.
关键词： theoretical spectroscopy,electronic structure,alkali antimonides,density-functional theory
更新于2025-09-09 09:28:46