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- 2018
- differential low noise amplifier
- GaAs pHEMT
- Square Kilometre Array (SKA)
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- Academia Sinica
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[IEEE 2019 Compound Semiconductor Week (CSW) - Nara, Japan (2019.5.19-2019.5.23)] 2019 Compound Semiconductor Week (CSW) - Structural and optical properties of GaAs film grown on a glass substrate using a large-grained Ge seed layer for solar cell applications
摘要： We fabricate a light absorbing GaAs layer on a glass substrate using a Ge seed layer formed by Al-induced crystallization. The GaAs layer grown at 520 °C exhibits the grain size of 50 μm and the internal quantum efficiency of 60% with a bias voltage of 1.0 V. These values are the largest among the GaAs layers grown on amorphous substrates at low temperatures (< 600 °C).
关键词： Al-induced crystallization,GaAs epitaxy,Thin film solar cell
更新于2025-09-23 15:21:01
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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) - Hot-Carrier Extraction in InAs/GaAs Quantum Dot Superlattice Solar Cells
摘要： We demonstrated hot-carrier (HC) extraction in GaAs solar cells containing InAs/GaAs quantum dot superlattices (QDSLs) functioning as a light absorber at 15 K. The short-circuit current density and the open-circuit voltage in the QDSL solar cells show step-wise changes as a function of the excitation photon density because of state filling under below-bandgap excitation. Furthermore, the short-circuit current density and the open-circuit voltage originated from the HC extraction were enhanced by increasing the period of the QDSL due to the improved absorptivity.
关键词： InAs quantum dots,GaAs,quantum dot superlattices,energy-selective barrier,hot-carrier solar cells
更新于2025-09-23 15:21:01
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Spatio-temporal coherence in vertically emitting GaAs-based electrically driven polariton lasers
摘要： We report on the implementation of a GaAs-based, vertically emitting electrically pumped polariton laser operated at cryogenic temperatures. The structure consists of a high quality factor AlGaAs/AlAs microcavity (Q ? 15 000) with two stacks of four GaAs quantum wells and features a Rabi splitting of 11 meV. Polariton lasing manifests by a clear threshold in the input–output characteristics of our device with a sharp drop in the emission linewidth and a continuous blueshift of 0.7 meV above threshold with increasing injection current. We measure spatial and temporal coherence of our device in the condensed phase by utilizing interference spectroscopy. Our results clearly demonstrate that electrically driven polariton lasers have promise as monolithic polaritonic sources of coherent light.
关键词： electrically pumped polariton laser,Rabi splitting,coherence,GaAs-based,microcavity
更新于2025-09-23 15:21:01
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Light trapping for photovoltaic cells used for optical power transmission
摘要： Photovoltaic (PV) cells used for optical power transmission convert laser light incident from limited directions to electricity. This illumination condition is in contrast to that for solar cells. A combination of an angular selective filter consisting of a dielectric multilayer on the front surface and a diffuse reflector on the rear surface significantly traps both the incident laser light into and radiation from the PV cell. This light trapping effect can improve the monochromatic conversion efficiency of a GaAs PV cell by 9% (absolute) compared with that for the ×4n2 trapping, under 872 nm and 1 W cm?2 laser illumination.
关键词： GaAs,light trapping,conversion efficiency,optical power transmission,photovoltaic cells
更新于2025-09-23 15:21:01
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High-Performance Enhancement of a GaAs Photodetector Using a Plasmonic Grating
摘要： In this study, we present and establish a gold surface plasmon polariton (SPP) GaAs photodetector that achieves high internal quantum efficiency (IQE). At a wavelength of 600 nm, the IQE with the SPP was 85%, while the IQE without the SPP was 42%, an enhancement of 43%. Also, at a wavelength of 675 nm, the IQE with SPP was 82%, whereas the IQE without SPP was 45%, which constitutes an increase of 37%. Such excellent performance is ascribed to the subwavelength scope of the optical power in the photoconductive-based gold SPP GaAs that provides high IQE. Moreover, the recombination of the SPP in the photodetector provides greater photocurrent and responsivity.
关键词： Surface plasmon polaritons,GaAs photodetector,Plasmonic photodetectors,Light trapping,Plasmonic grating
更新于2025-09-23 15:21:01
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Higha??temperature droplet epitaxy of symmetric GaAs/AlGaAs quantum dots
摘要： We introduce a high–temperature droplet epitaxy procedure, based on the control of the arsenization dynamics of nanoscale droplets of liquid Ga on GaAs(111)A surfaces. The use of high temperatures for the self-assembly of droplet epitaxy quantum dots solves major issues related to material defects, introduced during the droplet epitaxy fabrication process, which limited its use for single and entangled photon sources for quantum photonics applications. We identify the region in the parameter space which allows quantum dots to self–assemble with the desired emission wavelength and highly symmetric shape while maintaining a high optical quality. The role of the growth parameters during the droplet arsenization is discussed and modeled.
关键词： GaAs/AlGaAs,quantum photonics,arsenization dynamics,high–temperature droplet epitaxy,quantum dots
更新于2025-09-23 15:21:01
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Ultrathin films of L1 <sub/>0</sub> -MnAl on GaAs (001): A hard magnetic MnAl layer onto a soft Mn-Ga-As-Al interface
摘要： Ferromagnetic MnAl (L10-MnAl phase) ultrathin films with thickness varying from 1 to 5 nm have been epitaxially grown on a GaAs (001) substrate. A coercivity above 8 kOe has been obtained with no need of a buffer layer by tuning the sample preparation and the growth parameters. Surface and interface analysis carried out by in situ characterization techniques (x-ray photoelectron spectroscopy and low energy electron diffraction), available in the molecular beam epitaxy chamber, has shown the formation of a ferromagnetic interface consisting of Mn-Ga-As-Al, which contribution competes with the MnAl alloyed film. The appearance of this interface provides important information to understand the growth mechanism of MnAl-based films reported in the literature.
关键词： x-ray photoelectron spectroscopy,ferromagnetic,GaAs,molecular beam epitaxy,low energy electron diffraction,ultrathin films,L10-MnAl
更新于2025-09-23 15:21:01
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Effect of illumination on quantum lifetime in GaAs quantum wells
摘要： Low-temperature illumination of a two-dimensional electron gas in GaAs quantum wells is known to greatly improve the quality of high-field magnetotransport. The improvement is known to occur even when the carrier density and mobility remain unchanged, but what exactly causes it remains unclear. Here, we investigate the effect of illumination on microwave photoresistance in low magnetic fields. We find that the amplitude of microwave-induced resistance oscillations grows dramatically after illumination. Dingle analysis reveals that this growth reflects a substantial increase in the single-particle (quantum) lifetime, which likely originates from the light-induced redistribution of charge enhancing the screening capability of the doping layers.
关键词： quantum lifetime,microwave photoresistance,GaAs quantum wells,illumination effect,two-dimensional electron gas
更新于2025-09-23 15:21:01
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Detectors on the Basis of High-Purity Epitaxial GaAs Layers for Spectrometry of X and Gamma Rays
摘要： The characteristics of detectors of soft-X and γ rays based on high-purity epitaxial GaAs layers are discussed. The characteristics of detectors with different rectifying contacts are compared, that is, those with a Schottky barrier and a p–n junction. The spectral characteristics of the manufactured detectors that were obtained under the irradiation by 57Co and 241Am sources at different bias voltages and in a photovoltaic mode and the simulation results using the Geant 3.21 software package are presented.
关键词： photovoltaic mode,Geant 3.21,Schottky barrier,high-purity epitaxial GaAs layers,spectrometry,X and Gamma Rays,p–n junction
更新于2025-09-23 15:21:01
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DESIGN OF SUB-HARMONIC MIXER MMIC FOR EHF SATELLITE LINKS
摘要： This paper presents the design ?ow of a compact GaAs MMIC for Extremely High Frequency (EHF) satellite communications. The proposed circuit enables sub-harmonic mixing capability and integrates a LO bu?ering section, thus allowing for low frequency and low power reference signal interface. Circuit design is described in detail providing a comprehensive view of the followed theoretical approach, starting from mixer core de?nition until the complete synthesis of LO/RF/IF interfaces. In particular, the design ?ow of an innovative three-conductor Marchand balun is deeply analysed. Fabricated MMIC operates in the 43.5–50 GHz band and results in a compact layout (2.4 × 2.4 mm2) featuring a port-to-port isolation better than 25 dB with a typical conversion loss of 12 dB.
关键词： Marchand balun,sub-harmonic mixing,EHF satellite communications,GaAs MMIC,compact layout
更新于2025-09-23 15:21:01