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[IEEE 2019 International Conference on Power Generation Systems and Renewable Energy Technologies (PGSRET) - Istanbul, Turkey (2019.8.26-2019.8.27)] 2019 International Conference on Power Generation Systems and Renewable Energy Technologies (PGSRET) - Performance Comparison of (GaAS/GaAs) and (InGaP/GaAs) Tunnel Junction in Multi-Junction Solar Cells
摘要： This study presents a comparison of the performance of two multi-junction solar cells in terms of simulated short-circuit current density, open circuit voltage, efficiency and fill factor one of these cells with an InGaP / GaAs structure with a GaAs / GaAs junction tunnel and the other with the same structure but with an InGaP / GaAs hetrojunction tunnel. The silvaco-ticad software has been used to analyze and study these performances for both solar cells, the total thickness is specified to 0.66μm of top solar cell (GaInP), and the thickness of bottom solar cell (GaAs) is 2.64 μm and the tunnel junction with thickness 0.040 μm. He result of the simulation exposures for these multiple junction solar cells gives a conversion efficiency maximum of 24.2343% (AM1.5) would be obtained by choosing the p-In0.5Ga0.5P/n-GaAs tunnel heterojunction.
关键词： silvaco-ticad,tunnel junction,conversion efficiency,InGaP/GaAs,multi-junction solar cell
更新于2025-09-11 14:15:04
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Effect of confinement potential shape on the electronic, thermodynamic, magnetic and transport properties of a GaAs quantum dot at finite temperature
摘要： The effect of the shape of the confinement potential on the electronic, thermodynamic, magnetic and transport properties of a GaAs quantum dot is studied using the power-exponential potential model with steepness parameter p. The average energy, heat capacity, magnetic susceptibility and persistent current are calculated using the canonical ensemble approach at low temperature. It is shown that for soft confinement, the average energy depends strongly on p while it is almost independent of p for hard confinement. The heat capacity is found to be independent of the shape and depth of the confinement potential at low temperatures and for the magnetic field considered. It is shown that the system undergoes a paramagnetic-diamagnetic transition at a critical value of the magnetic field. It is furthermore shown that for low values of the potential depth, the system is always diamagnetic irrespective of the shape of the potential if the magnetic field exceeds a certain value. For a range of the magnetic field, there exists a window of p values in which a re-entrant behavior into the diamagnetic phase can occur. Finally, it is shown that the persistent current in the present quantum dot is diamagnetic in nature and its magnitude increases with the depth of the dot potential but is independent of p for the parameters considered.
关键词： transport properties,thermodynamic properties,canonical ensemble approach,electronic properties,quantum dot,GaAs,paramagnetic-diamagnetic transition,persistent current,magnetic properties,power-exponential potential model,confinement potential
更新于2025-09-11 14:15:04
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Bound-to-continuum intraband transition properties in InAs/GaAs quantum dot superlattice solar cells
摘要： We studied the interband and intraband excitation densities and the polarization dependent photocurrent in InAs/GaAs quantum dot superlattice (QDSL) solar cells with a built-in electric field of 5 kV cm?1. An almost polarization-insensitive intraband transition was observed for normal incident light, whereas slight anisotropy in the intraband transition resulted from the mixing between the conduction and valence bands. Furthermore, saturable two-color photocurrent was observed in the p–i–n solar-cell device because of electron transport in the QDSL miniband.
关键词： intraband transition,polarization anisotropy,quantum dot superlattice,solar cells,InAs/GaAs
更新于2025-09-11 14:15:04
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Interfacial properties of Hg <sub/>2</sub> CuTi-type Heusler alloy Ti <sub/>2</sub> NiAl/GaAs(100) heterojunction
摘要： For Hg2CuTi-type Inverse-Heusler alloy Ti2NiAl/GaAs(100) tunnel heterojunction, the magnetism, density of states and spin polarization of atoms at the interface were investigated systematically based on the first-principle calculation within the density functional theory (DFT). The calculated results reveal that the interface states seriously destroy the structural half-metallicity and lead to the spin polarization less than 60%. Among all of calculational hetero-structures, only the heterojunction with TA-ATⅡ structure still retains nearly 60% spin polarization, which is expected for further application in Tunnel Magneto resistance (TMR) devices.
关键词： first-principle calculation,Hg2CuTi-type Heusler alloy,TMR devices,Ti2NiAl/GaAs(100) heterojunction,spin polarization
更新于2025-09-11 14:15:04
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Selective Epitaxial Growth of GaAs on a Si (001) Surface Formed by an <i>In Situ</i> Bake in a Metal-Organic Chemical Vapor Deposition Reactor
摘要： We here report selective epitaxial growth of GaAs layers on Si (001) substrate with V-grooved trench using the aspect ratio trapping method. The V-grooved Si surface on the bottom of Si trenches was formed through a high temperature in situ baking process in H2 atmosphere before growth of GaAs in a metal-organic chemical vapor deposition (MOCVD) chamber. The evolution of the V-grooved shape and the density of defects in selectively grown GaAs epitaxial layers are reported as a function of high temperature bake times before GaAs growth by using both high resolution transmission electron microscopy (HR-TEM) and X-ray diffraction (XRD).
关键词： V-Grooved Si,Selective Epitaxial Growth,MOCVD,GaAs
更新于2025-09-11 14:15:04
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Electronic structures and optical gain of dilute nitride GaAs nanowires
摘要： The electronic structures and optical gain of GaAs1%xNx nanowires are calculated via the band anticrossing model together with the eight-band k & p theory. We ?nd that the optical gain spectra show an obvious red shift, and the gain increases slightly with increasing nitrogen content. The transverse magnetic (TM) gain is approximately 8.5 times larger than the transverse electric (TE) gain when the radius R is 3 nm, which indicates that GaAs1%xNx nanowires can be used as TM linearly polarized lasers in the near-infrared range. However, when R is 6 nm, the TM gain approaches the corresponding TE gain. In this case, GaAs1%xNx nanowires are not suitable for linearly polarized lasers.
关键词： optical gain,electronic structures,GaAs nanowires,dilute nitride,band anticrossing model,k & p theory
更新于2025-09-10 09:29:36
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Design of a MMIC low-noise amplifier in industrial gallium arsenide technology for E-band 5G transceivers
摘要： The technology, design procedure and measurements of an E-band (71-86 GHz) high performance gallium arsenide (GaAs) low-noise amplifier (LNA) are presented. The latter provides a gain in excess of 20 dB, an average in-band noise figure (NF) of 2.3 dB, absorbing 60 mW DC bias power. A European space-qualified technology (OMMIC’s GaAs 70 nm process) has been selected to demonstrate the feasibility of employing the proposed LNA for production-ready wireless backhaul point-to-point communication systems. A possible installation scenario has been depicted, in order to verify the maximum distance at which TX and RX antennas can be placed and employing the proposed LNA as first amplifying stage of the receiver chain.
关键词： LNA,GaAs,E-band,MMIC,millimeter wave circuits
更新于2025-09-10 09:29:36
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Temporal stability and absolute composition issues in molecular beam epitaxy of AlGaAs/GaAs THz QCL
摘要： The operation of the terahertz quantum cascade lasers (THz QCL) is strongly dependent on the repeatable fabrication of the well and barrier layers with the certain thicknesses throughout the whole active region stack epitaxial growth. This emphasizes the importance of the strict control of the growth rates and the stability of Si and group III effusion cell fluxes during growth [1]. It was reported [2] that two THz QCLs based on nominally identical multilayer heterostructures Al0.15Ga0.85As/GaAs emit at the different frequencies of 2.59 and 2.75 THz because of unintentional small deviations in the GaAs and AlAs growth rates (4 and 1.6 % respectively). Authors [3] determined the thickness tolerance for working lasing heterostructures to be minimally above 2% while the structures with thickness deviation 4.3 and 6.5 % are not lasing. In [4] the Ga cell temperature has to be increased to maintain a GaAs constant growth rate while the Al cell temperature remains nearly constant because variation in AlAs growth rate can be neglected. By using such growth rate compensation technique the two nominally identical structures approximately 10 mkm overall thick were found to show thickness difference of ~ 1 %. Thus calibration procedures and accurate analysis techniques become crucial to provide enhanced metrology possibilities.
关键词： molecular beam epitaxy,metrology,AlGaAs/GaAs,terahertz quantum cascade lasers,growth rates
更新于2025-09-10 09:29:36
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Charge and thermal modeling of a semiconductor-based optical refrigerator
摘要： Despite multiple attempts to achieve optical refrigeration in very high (99.5%) external quantum efficiency (EQE) GaAs, no cooling has been observed to date. In this study, we investigate optical refrigeration in GaAs by numerically solving the transient drift-diffusion equation coupled to Poisson’s equation. The charge carrier distributions we obtain, together with the heat diffusion equation, allow us to observe the spatial and temporal evolution of cooling/heating within GaAs. Our results indicate that maximum cooling occurs at a laser intensity different from that which maximizes EQE. An 11-fold difference in intensity exists with a corresponding 6-fold difference in cooling power. We ultimately find that samples suspended in vacuum using a 250 lm SiO2 fiber cool to 88 K, starting from room temperature. These results emphasize the critical importance of choosing an appropriate laser excitation intensity to achieve optical refrigeration along with minimizing the conductive heat load on the refrigerator. Furthermore, results of this study are applicable towards analyzing the optical response of other optoelectronic systems where accurate charge and/or heat diffusion modeling is critical.
关键词： drift-diffusion equation,external quantum efficiency,Poisson’s equation,cooling power,optical refrigeration,heat diffusion equation,GaAs
更新于2025-09-10 09:29:36
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Dislocations behavior in highly mismatched III-Sb growth and their impact on the fabrication of <i>top-down</i> n?+?InAs/p?+?GaSb nanowire tunneling devices
摘要： We study in this work the growth and fabrication of top-down highly doped n + InAs(Si)/p + GaSb(Si) Esaki tunneling diodes on (001) GaAs substrates. A careful investigation on the highly mismatched GaSb/GaAs growth is first conducted by means of Reflection High-Energy Electron Diffraction (RHEED), Atomic Force Microscopy (AFM), and X-Ray Diffraction (XRD) analyses. These results are expected to pave the way to methods for III-Sb buffer layer’s integration with low threading dislocation (TD) densities. A comparison between AFM, XRD, defect revealing by chemical etching and transmission electron microscopy (TEM) is then presented to calculate the precise TD density and its influence on the device structure. In the last part, we report on first operating sub-30 nm III-V vertical NW tunneling devices on (001) commercial GaAs substrates.
关键词： III-Sb growth,AFM,dislocations,TEM,nanowire tunneling devices,XRD,RHEED,GaAs substrates
更新于2025-09-10 09:29:36