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- differential low noise amplifier
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - High Sensitivity Heterodyne Electro-Optic Sampling with 1.5-μm Laser Source
摘要： A detection module for the heterodyne electro-optic sampling of terahertz pulses composed of a GaAs plate inserted into a tapered parallel plate waveguide has been designed and fabricated. The detector was installed into a standard terahertz time-domain spectrometer with a 1.5-μm femtosecond laser as a light source. The spectral bandwidth of 3.5 THz and dynamic range of 5 orders of magnitude were experimentally demonstrated, even with a photo-conductive antenna designed for 800-nm as an emitter.
关键词： 1.5-μm femtosecond laser,GaAs plate,tapered parallel plate waveguide,heterodyne electro-optic sampling,terahertz pulses,terahertz time-domain spectrometer
更新于2025-09-16 10:30:52
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Plasmonic nonlinearity in GaAs/In <sub/>0.20</sub> Ga <sub/>0.80</sub> As core/shell nanowires
摘要： We have investigated the plasmonic response of GaAs/In0.20Ga0.80As core/shell nanowires driven resonantly by strong THz fields with the amplitude of few MV/cm. The plasmon mode exhibits a systematic redshift with the suppression of the spectral weight with the increase of the driving THz field. Interestingly, the scaling of the plasmon parameters does not follow the usual quadratic behavior, indicating inhomogeneous intervalley electron scattering across the nanowire.
关键词： THz fields,intervalley electron scattering,GaAs/In0.20Ga0.80As,Plasmonic nonlinearity,core/shell nanowires
更新于2025-09-16 10:30:52
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Multi-Energy Valley Scattering Characteristics for a SI-GaAs-Based Terahertz Photoconductive Antenna in Linear Mode
摘要： In this paper, the relationship between the terahertz radiation and the spatial distribution of photogenerated carriers under different bias electric field is studied. Terahertz pulses and the photocurrent of SI-GaAs photoconductive antenna are measured by the terahertz time-domain spectroscopy system. The occupancy rate for photogenerated carriers for different energy valleys is obtained by comparing the photocurrent of terahertz field integrating with respect to time with the photocurrent measured by oscilloscope. Results indicate that 93.04% of all photogenerated carriers are located in the Γ valley when the bias electric field is 3.33 kV/cm, and 68.6% of all photogenerated carriers are transferred to the satellite valley when the bias electric field is 20.00 kV/cm. With the bias electric field increasing, the carrier occupancy rate for the satellite valley tends to saturate at 72.16%. In order to obtain the carrier occupancy rate for the satellite valley and saturate value at the high bias electric field, an ensemble Monte Carlo simulation based on the theory of photo-activated charge domain is developed.
关键词： photoconductive antenna,multi-energy valley scattering,semi-insulating Gallium arsenide (SI-GaAs),terahertz time-domain spectroscopy
更新于2025-09-16 10:30:52
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Dislocation reduction in AlInSb mid-infrared photodiodes grown on GaAs substrates
摘要： We investigated the electrical and optical properties of a highly mismatched AlInSb/GaAs photodiode sensor working in the mid-infrared range at room temperature. A substantial increase in the device performance was achieved by controlling the strain energy density in the dislocation ?lter layers and barrier layers to reduce the density of threading and interfacial dislocations, respectively. The resulting photodiode showed a high resistance-area product of 0.24 Ω cm2 and a peak detectivity of 2.2 × 109 cm Hz1/2 W–1 at 3.3 μm.
关键词： AlInSb,GaAs substrates,photodiode,dislocation reduction,mid-infrared
更新于2025-09-16 10:30:52
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Enhancing Photovoltaic Performance of GaAs Single-Junction Solar Cells by Applying a Spectral Conversion Layer Containing Eu-Doped and Yb/Er-Doped Phosphors
摘要： In this study, we examined e?orts to increase the photovoltaic performance of GaAs single-junction solar cells using spectral conversion layers, respectively, composed of europium-doped (Eu-doped) phosphors, ytterbium/erbium-doped (Yb/Er-doped) phosphors, and a combination of Eu-doped and Yb/Er-doped phosphors. Spin-on ?lm deposition was used to apply the conversion layers, all of which had a total phosphor concentration of 3 wt%. The chemical compositions of the phosphors were examined by energy-dispersive X-ray spectroscopy. The ?uorescence emissions of the phosphors were con?rmed by using photoluminescence measurements. Under laser diode excitation at 405 nm, we observed green luminescent downshift (LDS) emissions by Eu-doped phosphors at wavelengths of 479 nm to 557 nm, and under excitation at 980 nm, we observed red up-conversion (UC) emissions by Yb/Er-doped phosphors at wavelengths of 647 nm to 672 nm. The spectral conversion layers were characterized in terms of optical re?ectance, external quantum e?ciency, and photovoltaic current and voltage under AM 1.5 G simulations. The conversion e?ciency of the cell combining Eu-doped and Yb/Er-doped phosphors (23.84%) exceeded that of the cell coated with Yb/Er-doped phosphors (23.72%), the cell coated with Eu-doped phosphors (23.19%), and the cell coated without phosphors (22.91%).
关键词： ytterbium/erbium-doped (Yb/Er-doped),europium-doped (Eu-doped),up-conversion,phosphors,GaAs solar cell,luminescent downshift
更新于2025-09-16 10:30:52
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[IEEE 2019 34th Symposium on Microelectronics Technology and Devices (SBMicro) - Sao Paulo, Brazil (2019.8.26-2019.8.30)] 2019 34th Symposium on Microelectronics Technology and Devices (SBMicro) - Investigation of the quantum confinement anisotropy in a submonolayer quantum dot infrared photodetector
摘要： A submonolayer quantum dot infrared photodetector (SML-QDIP) was grown on a GaAs(001) substrate by molecular beam epitaxy and processed using conventional optical lithography, wet etching and electron-beam metallization. Additionally, a side of the device was polished at 45 degrees in order to allow optical measurements with s- and p- polarized light. The electro-optical properties of the device were investigated both in normal incidence and at 45 degrees in order to study the quantum confinement of the SML-QD along the lateral and vertical directions. The s-to-p photocurrent ratio was found to be between 0.10 and 0.43, showing that, in this new type of quantum dot, the lateral confinement is still weaker than along the vertical direction, but is better than the one of conventional QDs fabricated in the Stranski-Krastanov growth mode. The maximum specific detectivity in normal incidence was 1.3×1011 cm Hz1/2/W at 30 K and 0.9V.
关键词： quantum dot,GaAs,molecular beam epitaxy,infrared detector,photolithography,submonolayer
更新于2025-09-16 10:30:52
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[IEEE 2018 Australasian Universities Power Engineering Conference (AUPEC) - Auckland, New Zealand (2018.11.27-2018.11.30)] 2018 Australasian Universities Power Engineering Conference (AUPEC) - Nano-structured GaAs Solar Cell Design, Simulation and Analysis for Conversion Efficiency Improvement
摘要： This paper discusses nano-structured GaAs solar cell design and analysis for conversion efficiency improvement by increasing the light transmission and absorption, reducing the light reflection. The focus of this research is to construct different type of nano-grating shaped GaAs solar cells with various nano-grating heights and pitches, to compare the simulation results and find a suitable nano-structure that can provide higher conversion efficiency. Finite difference time domain (FDTD) simulation tool is used to simulate and calculate transmission and absorption for different nano-grating shapes, such as, parabolic, triangular, trapezoidal and rectangular. Based on the simulation results, it has been confirmed that the light reflection of parabolic shaped nano-grating structures is higher than triangular nano-grating structures, but it is lower than rectangular and trapezoidal shaped nano-grating structures. Moreover, the simulation results confirmed that the light transmission of parabolic shaped nano-grating structures is about 62.3% having a 200-nm grating height and an 810-nm grating pitch, which is about 22% higher than the rectangular (i.e., flat) type substrates.
关键词： Finite-difference time-domain method,transmission,GaAs solar cells,and absorption,Nano-grating structure,Light reflection,Conversion efficiency,Solar or renewable energy
更新于2025-09-16 10:30:52
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AlGaAs/GaAs solar cell with CNT transport layer: numerical simulation
摘要： AlGaAs/GaAs solar cells (SC) was modeled. Conventional SC was compared with structure with the thinner emitter. SC with additional CNT transport layer was simulated and compared with SC without it. The simulation was carried out with different geometry of the contacts and light flux. CNT transport layer has allowed achieving an increase in SCs efficiency up to 1.7% compared with metal contact grid.
关键词： CNT transport layer,numerical simulation,AlGaAs/GaAs solar cell
更新于2025-09-16 10:30:52
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Efficient and Range-Variable Laser Wireless Charging Technology
摘要： The conversion efficiency of photovoltaic cells, charging distance and tracking technology are three important indicators of laser wireless charging technology. This paper demonstrates an efficient laser wireless charging scheme with variable charging distance and a simple tracking system. The laser wireless charging system proposed in this paper is mainly composed of 808nm laser, zoom beam expander, GaAs photovoltaic cell and the energy management module. By increasing the uniformity of laser spot energy distribution, the conversion efficiency of GaAs photovoltaic cells reaches 35.3%. Reduce system cost by simplifying the tracking system. Using zoom beam expander, the charging distance ranges from 10 to 50 meters.
关键词： GaAs photovoltaic cell,Zoom beam expander,Tracking system,Laser wireless charging
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE 4th Optoelectronics Global Conference (OGC) - Shenzhen, China (2019.9.3-2019.9.6)] 2019 IEEE 4th Optoelectronics Global Conference (OGC) - Quality Assessment of 980 nm GaAs Based Laser Diodes with Use of Low-Frequency Noise Measurements
摘要： Low-frequency noise has always been a fast and non-destructive tool to characterise the performance and quality of materials and electrical devices. In this paper, a non- destructive method of predicting reliability was introduced for 980 nm GaAs based semiconductor laser diodes. Measurement and analysis were carried out for the noise and transport characteristics of forward voltage biases. The results demonstrated a close relationship between LD quality and the characteristic parameters of low-frequency noise such as frequency exponent, noise intensity and amplitude.
关键词： low-frequency noise,frequency exponent,forward bias,laser diodes,GaAs substrate
更新于2025-09-16 10:30:52