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The spin-wave stiffness D of ferromagnetic systems represents an important micromagnetic parameter closely related to exchange interactions between local magnetic moments.
We study the exciton emission from ensembles of uncoated and plasmonic gold/aluminum quinoline (Alq3) coated GaAs-AlGaAs-GaAs core-shell nanowires (NWs) and GaN nanorods using time-integrated (TI) as well as time resolved (TR) photoluminescence (PL). The ∼ 150nm diameter zincblende NWs were grown on GaAs substrate using the Au catalyzed vapor-liquid-solid method. The wurtzite GaN nanorods of ∼ 250nm...
Epitaxial lateral overgrowth (ELOG) of GaInP on GaAs by hydride vapor phase epitaxy (HVPE) is carried out as a pre-study to obtain GaInP/Si heterointerface. We present first results on the growth of GaInP/Si by a modified ELOG technique, corrugated epitaxial lateral overgrowth (CELOG).
We have successfully mitigated the out-diffusion of Ge during molecular beam epitaxy of InGaAs on Ge by using a GaAsSb layer as evidenced by secondary ion mass spectroscopy. Compared to GaAs, this GaAsSb layer also provides a smoother surface morphology with its root mean square roughness of 0.664 nm. Using a GaAsSb step-graded buffer (SGB) and an AlGaAsSb high resistivity buffer, we are able to grow...
In this contribution we present our recently developed “reverse-reaction-growth” scheme in molecular beam epitaxy to fabricate 1D GaAs nanowires (NWs) with diameters down to 7 nm. We observe the presence of strong quantum confinement phenomena, opening the path towards a true 1D NW platform. The introduction of crystal defects in the NW effectively leads to bright and spectrally sharp crystal phase...
A photoconductive semiconductor switch (PCSS) with a gap of 2 mm was fabricated on a semi-insulating GaAs substrate. The PCSS was excited by a 1064 nm wavelength pulse laser which has 700 ps pulse width (FWHM) and energy of 135 µJ. Output pulses of the PCSS were recorded at bias voltages from 100 V to 1.4 kV in fluorinert ambience which has high dielectric strength (Eb > 160 kV/cm). At bias voltages...
A reconfigurable metamaterial analog electromagnettically induced transparency like (EIT-like) effect is theoretically and numerically demonstrated in this paper. The unit cell is composed of a stimulated circular loop element and an unstimulated arc slot element, which are both constructed by semiconductor. The proposed designs can realize a continuously tunable EIT-like effect in a broad frequency...
GaAs films were grown with molecular beam epitaxy (MBE) method on Si substrates defected from plane (001) at 6° towards [110]. The processes of epitaxial layers nucleation and growth were controlled with the RHEED method. Investigations of the crystallographic properties of the grown structures were carried out by the methods of X-ray diffractometry and transmission electron microscopy (TEM). It is...
An inverted GaAs solar cell structure has been grown with the MBE method. Together with the substrate, the structure was glued to a polymer film of polyethylene terephthalate (PET film) by means of epoxy resin. After the removal of the substrate, the contact platforms were created and the light window was opened. Research of the solar cell photovoltaic properties was conducted at non-concentrated...
A new strain-balanced multiple quantum well (MQW) approach to tune the Ga0.51In0.49P bandgap is demonstrated. This approach is based on Ga1−xInxP/Ga1−yInyP (x > y) or Ga1−xInxAszP1−z/Ga1−yInyP (x > y) structures, strain balanced and lattice matched to GaAs in a p-i-n solar cell structure. A red shift in the absorption edge and an increase in the short circuit current were observed. Carriers...
Binary information encoded within the spin of carriers can be transferred into corresponding right or left-handed circularly polarized photons emitted from an active semiconductor medium via carrier-photon angular momentum conversion. In order to attain maximized spin-injection at out-of-plane magnetic remanence, a number of material systems have been explored as possible solid-state spin injectors...
The charge collection probability is one of the most important parameters of a solar cell. We derived two kinds of special functions to fit the external quantum efficiency and use then to reconstruct the charge collection probability. The simulation results of gallium arsenide and silicon solar cells are put into comparison.
We present the carrier transport properties in the double-barrier InAs quantum dots and InGaAs quantum well hybrid structure of the photoelectric device and analyze the capacitance hysteresis phenomenon. Due to the coupling effect among multiple quantum dots, the I–V and C-V curves measured of the photoelectric device shows the capacitance changes with the light intensity. We analyze the relationships...
Eigenstates and intersubband transition energies of a T-shaped quantum wire embedded in square quantum wire are numerically computed by solving time-independent Schrödinger equation using finite difference technique. Dimensions of arm well and stem wells and material composition of shell layer is varied to observe the change in transition energies. AlxGa1−xAs/GaAs composition is considered for simulation...
InP-InxGa(1-x)As-InP quantum well tube (QWT) structures are grown on InP nanowires that are [100] oriented. The In mole fraction, x is varied between 0 and 1. The QWTs grown on the facets of the [100] nanowires that have {100} and {011} side facets forming an octagonal cross-section, are found to be highly non-uniform. Bright emission is observed at room temperature from these QWTs. Band-gap tunability...
We demonstrate an ${\rm Al}_{0.52}{\rm In}_{0.48}{\rm P}$ homo-junction Separate Absorption Multiplication Avalanche Photodiode as a detector with narrow spectral response in the blue-green part of the optical spectrum. Due to its wide band-gap, this device has a dark current density of < 8 nA ${\rm cm}^{-2}$ at 99.9% of the breakdown voltage at room temperature. This device has a peak responsivity...
This paper reports electrical characteristics of an intermediate band p-i-n GaAs solar cell with InAs quantum dots embedded in the intrinsic region using Synopsis TCAD simulation tools. Up to five layers of quantum dots have been taken into consideration and modeled. Also, the size of the quantum dots has been varied from 10 to 60 nm to understand the effects of quantum dot density. The short-circuit...
The wavelength limit (λc) of detection in a conventional photodetector is limited to a characteristic energy (Δ) through the relationship: λc = hc/Δ, where Δ also determines the detector noise (dark current) and hence its performance such as the operating temperature. Here, we report an infrared photodetector with an extended operating range (responding beyond the standard spectral threshold) based...
The properties of III–V compound semiconductors and their heterojunctions have been relentlessly investigated due to their wide-ranging applications in electronic and optoelectronic technologies. One of most important electronic property of heterojunctions is the band offset which describes the relative alignment of the electronic bands across the junction interface. Accurate determination of band...
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