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- 2018
- differential low noise amplifier
- GaAs pHEMT
- Square Kilometre Array (SKA)
- fully- integrated
- balun
- broadband
- S-band
- Electronic Science and Technology
- National Taiwan University
- Academia Sinica
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Near-Infrared Lasing at 1 μm from a Dilute-Nitride-Based Multishell Nanowire
摘要： A coherent photon source emitting at near-infrared (NIR) wavelengths is at the heart of a wide variety of applications ranging from telecommunications, optical gas sensing to biological imaging, and metrology. NIR-emitting semiconductor nanowires (NWs), acting both as a miniaturized optical resonator and as a photonic gain medium, are among the best-suited nanomaterials to achieve such goals. In this study, we demonstrate the NIR lasing at 1 μm from GaAs/GaNAs/GaAs core/shell/cap dilute nitride nanowires with only 2.5 % of nitrogen. The achieved lasing is characterized by an 'S'-shape pump-power dependence and narrowing of the emission line-width. Through examining the lasing performance from a set of different single NWs, a threshold gain, g_th, of 4100 – 4800 cm^{-1}, was derived, with a spontaneous emission coupling factor, β, up to 0.8, which demonstrate the great potential of such nanophotonic material. The lasing mode was found to arise from the fundamental HE11a mode of the Fabry-Perot cavity from a single NW, exhibiting optical polarization along the NW axis. Based on temperature dependence of the lasing emission, a high characteristic temperature, T_0, of 160(±10) K is estimated. Our results, therefore, demonstrate a promising alternative route to achieve room-temperature NIR NW lasers thanks to the excellent alloy tunability and superior optical performance of such dilute nitride materials.
关键词： dilute nitride,GaAs/GaNAs/GaAs,core/shell/cap structure,Nanowire lasers
更新于2025-09-23 15:23:52
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Simulation of GaAs Nanowire Growth and Crystal Structure
摘要： Growing GaAs nanowires with well defined crystal structures is a challenging task, but may be required for the fabrication of future devices. In terms of crystal phase selection, the connection between theory and experiment is limited, leaving experimentalists with a trial and error approach to achieve the desired crystal structures. In this work, we present a modelling approach designed to provide the missing connection, combining classical nucleation theory, stochastic simulation and mass transport through the seed particle. The main input parameters for the model are the flows of the growth species and the temperature of the process, giving the simulations the same flexibility as experimental growth. The output of the model can also be directly compared to experimental observables, such as crystal structure of each bilayer throughout the length of the nanowire and the composition of the seed particle. The model thus enables for observed experimental trends to be directly explored theoretically. Here, we use the model to simulate nanowire growth with varying As flows, and our results match experimental trends with good agreement. By analysing the data from our simulation, we find theoretical explanations for these experimental results, providing new insights into how the crystal structure is affected by the experimental parameters available for growth.
关键词： Wurtzite,Zinc Blende,GaAs,Nanowire,Simulation
更新于2025-09-23 15:23:52
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Formation and Characterization of Shallow Junctions in GaAs Made by Ion Implantation and ms-Range Flash Lamp Annealing
摘要： With the demand of aggressive scaling in nanoelectronics, further progress can be realized by integration of high mobility semiconductors, such as III–V compound semiconductors, with complementary metal-oxide-semiconductor (CMOS) technology. In this study, the formation of shallow n–p and p–n junctions in GaAs utilizing ion implantation of S and Zn, respectively, followed by millisecond-range flash lamp annealing (FLA) is presented. The distribution of implanted elements obtained by secondary ion mass spectrometry (SIMS) shows that the FLA process can effectively suppress the diffusion of dopants. Simultaneously, the ms-range annealing is sufficient to recrystallize the implanted layer and to activate the dopants. Formation of p–n and n–p junctions is confirmed by current–voltage characteristics. The ratio of reverse to forward current can reach up to 1.7 × 10^7 in the n-GaAs:Zn case.
关键词： GaAs,ion implantation,shallow junctions,flash lamp annealing
更新于2025-09-23 15:23:52
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Analysis of nonlinear large signal intrinsic elements for InGaP/GaAs HBT based on Gummel-Poon model
摘要： A large signal analysis method based on Gummel‐Poon model is proposed to predict nonlinear behavior of InGaP/GaAs HBT. A 2 × 20 μm2 transistor is fabricated with InGaP/GaAs HBT technology. The large signal transconductance Gm, conductance Gbe, and capacitance CBE, CBC are calculated based on the proposed method and measured using a RF testing probe. The calculated and measured results show good consistency up to nonlinear power level. The proposed method is applied to analyze variations of nonlinear large signal intrinsic elements of this transistor with increasing power under different bias conditions, in order to raise benefit of nonlinear consideration for power amplifiers.
关键词： Gummel‐Poon,nonlinear,large signal model,GaAs HBT
更新于2025-09-23 15:23:52
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Hard X-ray photoelectron spectroscopy investigation of annealing effects on buried oxide in GaAs/Si junctions by surface-activated bonding
摘要： Hard X-ray photoelectron spectroscopy measurements are performed on ≈10-nm-thick GaAs film/Si substrate junctions fabricated by the surface activated bonding and selective wet etching. The chemical shifts of Ga-O and As-O signals in Ga 2p3/2 and As 2p3/2 core spectra indicate that oxides are formed in a part of GaAs films neighboring GaAs/Si interfaces due to the surface activation process. Analyses of Ga-O and As-O signals show that the thickness of such buried oxides is decreased due to a post-bonding annealing at temperatures up to 400 °C. This means that the electrical properties of bonding interfaces, which are in the meta-stable states, are improved by the annealing. The thickness of oxides is different from that of amorphous-like transition layers at the GaAs/Si interfaces observed by transmission electron microscopy.
关键词： Buried interface,Surface activated bonding,GaAs/Si,HAXPES
更新于2025-09-23 15:23:52
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High throughput MOVPE and accelerated growth rate of GaAs for PV application
摘要： We present the feasibility of metalorganic vapor phase epitaxy (MOVPE) with extremely high-speed growth of GaAs for solar cell applications. The growth rate was increased up to 120 μm/h, and exhibited an almost linear relationship with the amount of supplied trimethylgallium (TMGa). The thickness variation and doped carrier concentration of GaAs grown at 90 μm/h were comparable to those of conventionally grown GaAs at a lower growth rate. The potential for reducing the V/III supply ratio was investigated to reduce the material cost. Non-doped GaAs wafers were grown at the accelerated growth rate of 90 μm/h, with various V/III ratios. The growth rate of GaAs increased by 20% when the V/III ratio was decreased from 40 to 5. In low temperature photo-luminescence (PL) measurement, significant change in PL spectra was not observed, indicating that there was no significant change in quality. The light-power conversion efficiency was almost comparable for V/III ratios from 10 to 40 whereas that at the lowest V/III ratio of 5 was degraded. Photovoltaic (PV) solar cells of GaAs were fabricated with various growth condition. It is found that the performance of the cells grown at 90 μm/h were comparable with previous results.
关键词： A3. Metalorganic vapor phase epitaxy,B2. Semiconducting GaAs,B3. Solar cells,A1. Crystal morphology
更新于2025-09-23 15:23:52
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The contribution of AsH3: Pre-flow and V/III ratio effects on heteroepitaxially grown GaAs/Ge
摘要： We report the effects of AsH3 (arsine) on morphological, structural, optical and crystalline quality of MOVPE (metal organic vapor phase epitaxy) grown GaAs/Ge heterostructures. AsH3 pre-flow supplied on Ge substrate to have As atoms as a first atomic layer on the surface of Ge substrate. Additionally, the V/III ratio effects of LT-GaAs buffer layer, grown on arsenized Ge substrate, have been analyzed to have reduced APBs (anti-phase boundaries) in the interface between epilayer and Ge substrate. It has been considered that the optimal AsH3 pre-flow duration and V/III ratio of GaAs buffer layer extremely influence the effects of APBs even we have used miss-cut Ge substrate and grown by two-step growth technique to obtain double atomic step. It is shown that without AsH3 pre-flow the surface of GaAs epilayer becomes rougher while it is optically smooth under the longer AsH3 pre-flow. On the other hand, even the surface situation does not change with longer AsH3 pre-flow the structural, optical and crystalline qualities become worse because of the possible presence vacancies of created during the growth. Similar behavior has been observed for the V/III effects of GaAs buffer layer and it has resulted in low full width at half maximum of high-resolution X-ray diffraction and high photoluminescence peak intensity for the optimal V/III ratio.
关键词： Ge,Buffer layer,Arsine,MOVPE,GaAs
更新于2025-09-23 15:23:52
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X-ray Diffraction Analysis of the Angular Stability of Self-Catalyzed GaAs Nanowires for Future Applications in Solar Light Harvesting and Light Emission Devices
摘要： Semiconductor nanowires are a class of materials that recently have gained increasing interest in solar cell applications and light emitting devices. Finding reproducible processing conditions is fundamental for their future mass production. In this work, the stability of individual epitaxial GaAs nanowires (NWs) under molecular beam epitaxy (MBE) processing conditions is studied by means of a time-resolved in-situ micro X-ray diffraction (XRD) method and scanning electron microscopy. Our proposed micro XRD method is a non-destructive characterization technique where individual nano-objects of different dimensions, crystal orientations, and structures are detectable under MBE processing conditions. NWs were grown by self-catalyzed MBE onto pre-patterned Si(111) substrate. When exposed to MBE processing conditions at 610 °C without supply of source material, or with only arsenic supply, we observe evaporation from the facets with no indication of gallium droplet formation. Furthermore, the NWs, which are initially grown perpendicular to the substrate surface become angularly unstable i.e. the NWs tilt and eventually lie down on the substrate surface. Before falling down, our micro XRD data evidenced vibrations/bending of the NWs. Interestingly, when exposed to the original growth conditions which include gallium and arsenic supply, the vibrations/bending are suppressed and the tilting can be reversed. The findings in this paper can also provide insights towards engineering of self-catalyzed GaAs NW growth by removal of parasitic growth objects which inevitably grow together with NWs.
关键词： time-resolved,in-situ,mechanical stability,micro X-ray diffraction,nanowire,annealing,GaAs
更新于2025-09-23 15:23:52
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[IEEE 2018 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - Chengdu, China (2018.5.7-2018.5.11)] 2018 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - A Broadband 1-dB Noise Figure GaAs Low-Noise Amplifier for Millimeter-Wave 5G Base-Stations
摘要： A broadband low-noise amplifier (LNA) with sub-1 dB noise figure (NF), intended for use in millimeter-wave 5G base-stations, have been fabricated in 0.1-μm InGaAs pHEMT technology. Common-source topology with inductive source degeneration is utilized for simultaneous noise and input match. Measurement results show this LNA achieves a gain of 7.9 dB at 24-GHz and a -1 dB bandwidth of 5-GHz, while consuming 13 mW from a 1-V supply. The noise figure is below 1.5 dB from 21-GHz to 27-GHz, with a lowest noise figure of 0.7 dB at 26-GHz.
关键词： millimeter-wave,noise figure,pHEMT,5G,low-noise amplifier,GaAs
更新于2025-09-23 15:22:29
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Optical Properties and Carrier Transport in a Biased GaAs/AlAs Asymmetric Quintuple-Quantum-Well Superlattice
摘要： Photoluminescence (PL) properties and carrier transport in a GaAs/AlAs asymmetric quintuple-quantum well superlattice (AQQW-SL) were investigated. Since AQQWs are separated by very thin AlAs barriers, various carrier transport phenomena are expected due to the strong coupling of wave functions between the Γ states in the GaAs QWs and the X states in the AlAs barriers. A 20-period AQQW was embedded in the i-layer of a pin diode. A PL signal between the ground Γ and the heavy hole (hh) states was observed around 740 nm. However, another PL branch was observed at about 665 nm around 6 V. Based on the numerical calculation of the Γ and X wave functions, the electron transport from the X state in the thick AlAs barrier (X11) to the Γ state in the third QW (Γ31) occurs at 6.1 V. Thus, a PL signal at 665 nm can be attributed to the recombination between Γ31 and hh11.
关键词： GaAs/AlAs,photoluminescence,asymmetric quintuple-quantum-well,superlattices
更新于2025-09-23 15:22:29