5,180 research outputs found
The 20 and 30 GHz MMIC technology for future space communication antenna system
The development of fully monolithic gallium arsenide receive and transmit modules is described. These modules are slated for phased array antenna applications in future 30/20 gigahertz communications satellite systems. Performance goals and various approaches to achieve them are discussed. The latest design and performance results of components, submodules and modules are presented
Gallium arsenide (GaAs) power conversion concept
A summary design analysis of a GaAs power conversion system for the solar power satellite (SPS) is presented. Eight different satellite configuration options for the solar arrays are compared. Solar cell annealing effects after proton irradiation are considered. Mass estimates for the SPS and the effect of solar cell parameters on SPS array design are discussed
Peeled film GaAs solar cells for space power
Gallium arsenide (GaAs) peeled film solar cells were fabricated, by Organo-Metallic Vapor Phase Epitaxy (OMVPE), incorporating an aluminum arsenide (AlAs) parting layer between the device structure and the GaAs substrate. This layer was selectively removed by etching in dilute hydrofloric (HF) acid to release the epitaxial film. Test devices exhibit high series resistance due to insufficient back contact area. A new design is presented which uses a coverglass superstrate for structural support and incorporates a coplanar back contact design. Devices based on this design should have a specific power approaching 700 W/Kg
Probing Spin-Polarized Currents in the Quantum Hall Regime
An experiment to probe spin-polarized currents in the quantum Hall regime is
suggested that takes advantage of the large Zeeman-splitting in the
paramagnetic diluted magnetic semiconductor zinc manganese selenide
(ZnMnSe). In the proposed experiment spin-polarized electrons are
injected by ZnMnSe-contacts into a gallium arsenide (GaAs) two-dimensional
electron gas (2DEG) arranged in a Hall bar geometry. We calculated the
resulting Hall resistance for this experimental setup within the framework of
the Landauer-B\"uttiker formalism. These calculations predict for 100%
spininjection through the ZnMnSe-contacts a Hall resistance twice as high as in
the case of no spin-polarized injection of charge carriers into a 2DEG for
filling factor . We also investigated the influence of the equilibration
of the spin-polarized electrons within the 2DEG on the Hall resistance. In
addition, in our model we expect no coupling between the contact and the 2DEG
for odd filling factors of the 2DEG for 100% spininjection, because of the
opposite sign of the g-factors of ZnMnSe and GaAs.Comment: 7 pages, 5 figure
Gallium Arsenide (GaAs) Quantum Photonic Waveguide Circuits
Integrated quantum photonics is a promising approach for future practical and
large-scale quantum information processing technologies, with the prospect of
on-chip generation, manipulation and measurement of complex quantum states of
light. The gallium arsenide (GaAs) material system is a promising technology
platform, and has already successfully demonstrated key components including
waveguide integrated single-photon sources and integrated single-photon
detectors. However, quantum circuits capable of manipulating quantum states of
light have so far not been investigated in this material system. Here, we
report GaAs photonic circuits for the manipulation of single-photon and
two-photon states. Two-photon quantum interference with a visibility of 94.9
+/- 1.3% was observed in GaAs directional couplers. Classical and quantum
interference fringes with visibilities of 98.6 +/- 1.3% and 84.4 +/- 1.5%
respectively were demonstrated in Mach-Zehnder interferometers exploiting the
electro-optic Pockels effect. This work paves the way for a fully integrated
quantum technology platform based on the GaAs material system.Comment: 10 pages, 4 figure
Graphite based Schottky diodes formed on Si, GaAs and 4H-SiC substrates
We demonstrate the formation of semimetal graphite/semiconductor Schottky
barriers where the semiconductor is either silicon (Si), gallium arsenide
(GaAs) or 4H-silicon carbide (4H-SiC). Near room temperature, the forward-bias
diode characteristics are well described by thermionic emission, and the
extracted barrier heights, which are confirmed by capacitance voltage
measurements, roughly follow the Schottky-Mott relation. Since the outermost
layer of the graphite electrode is a single graphene sheet, we expect that
graphene/semiconductor barriers will manifest similar behavior.Comment: 5 pages, 3 figures, 1 tabl
Monolithic optical integrated control circuitry for GaAs MMIC-based phased arrays
Gallium arsenide (GaAs) monolithic microwave integrated circuits (MMIC's) show promise in phased-array antenna applications for future space communications systems. Their efficient usage will depend on the control of amplitude and phase signals for each MMIC element in the phased array and in the low-loss radiofrequency feed. For a phased array contining several MMIC elements a complex system is required to control and feed each element. The characteristics of GaAs MMIC's for 20/30-GHz phased-array systems are discussed. The optical/MMIC interface and the desired characteristics of optical integrated circuits (OIC's) for such an interface are described. Anticipated fabrication considerations for eventual full monolithic integration of optical integrated circuits with MMIC's on a GaAs substrate are presented
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