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The Aichi Synchrotron Radiation Center (AichiSR) is a research facility in Aichi Prefecture, Japan, owned by the Aichi Science and Technology Foundation (ASTF). It provides synchrotron light for research and development purposes, with several beamlines offering different types of X-ray measurements. The facility operates for 8.5 hours a day, four days a week, and accepts applications from users every other month. The majority of users are from industry, particularly in the field of R&D for automobiles. AichiSR has been successful in various research projects and plans to enhance its beamlines and develop new imaging technologies for the future. [Extracted from the article]

Research was conducted to investigate the Er-related luminescence in GaP:Er, grown by organometallic vapor phase epitaxy, at low temperature under above-band gap and below-band gap excitation. Photoluminescence spectra obtained under all experimental conditions were dominated by several sharp emission lines. Results suggest that some Er-related luminescence centers are activated by direct excitation of electrons to some traps related to the luminescence centers.

A one monolayer level study was conducted on the crystal and layer structures of an Er delta-doped layer in InP using an x-ray crystal truncation rod scattering measurement and synchroton radiation-based x-ray interference. Measurements and computer simulation reveal that the rocksalt structure ErP are developed by Er atoms delta-dpoed in InP. Results also show that the Er atoms are confined in 5 ML.

The effects of GaN quantum barriers with changing growth temperatures on the interfacial characteristics of GaN/InGaN single quantum well (SQW) grown on GaN templates by metalorganic vapour phase epitaxy were in situ investigated by X-ray crystal truncation rod (CTR) scattering and X-ray reflectivity measurements at growth temperature using a laboratory level X-ray diffractometer. Comparing the curve-fitting results of X-ray CTR scattering spectra obtained at growth temperature with that at room temperature, the InxGa1-xN with indium composition less than 0.11 was stabile of the indium distribution at the interface during the whole growth processes. By using several monolayers thickness GaN capping layer to protect the InGaN well layer within temperature-ramping process, the interfacial structure of the GaN/InGaN SQW was drastically improved on the basis of the curve-fitting results of X-ray CTR scattering spectra, and the narrow full width at half-maximum and strong luminous intensity were observed in room temperature photoluminescence spectra. [ABSTRACT FROM AUTHOR]

The indium supplied on c-plane GaN templates using Metal organic vapor phase epitaxy was studied by in situ X-ray reflectivity (XRR) at 800 °C. The presence of liquid indium layers on the GaN (0001) surface was demonstrated using data-fitting of XRR measurements, ex situ atomic force microscope, auger electron spectroscopy, and cross-sectional scanning electron microscope. These measurements demonstrated that a liquid indium layer coexisted with indium droplets on top of the GaN (0001) surface at 800 °C. The liquid indium film thicknesses increased with increasing TMIn supply time and did not change during cooling from 800 °C to room temperature. [ABSTRACT FROM AUTHOR]

The spin-polarization of electrons from the GaAs/GaAsP superlattice on a GaAs substrate (∼90%) is higher than that from the same superlattice on a GaP substrate (∼60%). Transmission electron microscopy and atomic force microscopy observations revealed that stacking faults were the main defects in the superlattice on the GaAs substrate, while local thickness modulation of the superlattice layers was prominent in the superlattice on the GaP substrate. According to the density of stacking faults and the areal ratio of the thickness modulation, it was concluded that the thickness modulation in the superlattice was the main reason for the spin-polarization reduction in the photocathode on the GaP substrate. Growth of a thin GaAs layer on a GaP substrate prior to superlattice growth eliminated the thickness modulation and the spin-polarization was recovered to 90%. [ABSTRACT FROM AUTHOR]

In order to produce a high brightness and high spin polarization electron beam, a pointlike emission mechanism is required for the photocathode of a GaAs polarized electron source. For this purpose, the laser spot size on the photocathode must be minimized, which is realized by changing the direction of the injection laser light from the front side to the back side of the photocathode. Based on this concept, a 20 kV gun was constructed with a transmission photocathode including an active layer of a GaAs–GaAsP superlattice layer. This system produces a laser spot diameter as small as 1.3 μm for 760–810 nm laser wavelength. The brightness of the polarized electron beam was ∼2.0×107 A cm-2 sr-1, which corresponds to a reduced brightness of ∼1.0×107 A m-2 sr-1 V-1. The peak polarization of 77% was achieved up to now. A charge density lifetime of 1.8×108 C cm-2 was observed for an extracted current of 3 μA. [ABSTRACT FROM AUTHOR]

Extremely low emittance electron beams are required for next generation accelerators. GaAs semiconductor photocathodes with negative electron affinity (NEA) surfaces have an intrinsic advantage for generating such low emittance beams and the thermal emittance as low as 0.1 π mm mrad is expected in ideal case. The thermal emittance of photoelectrons was measured for two different NEA photocathodes: a bulk-GaAs photocathode and a GaAs-GaAsP superlattice strained photocathode. The normalized root-mean-sqare emittances for the beam radius of 1.0 mm were as low as 0.20-0.29±0.02 and 0.15±0.02 π mm mrad, respectively. A comparison of these results shows that the superlattice photocathode minimizes the thermal emittance for photon excitation energies higher than the band gap energy. [ABSTRACT FROM AUTHOR]

Electron spin resonance (ESR) measurements of Zn-codoped GaAs:Er,O grown by organometallic vapor phase epitaxy have been performed at 9.49 GHz. Several anisotropic ESR signals (named as A, B, and C) are observed. The angular and temperature dependences of the A, B, and C signals are quite consistent with those observed in GaAs:Er,O. We found that the intensity of the C center decreases together with the decrease of the photoluminescence (PL) intensity by changing the doping amount of Zn, while the change of the ESR intensity of the B center is relatively small. This indicates that the Zn codoping selectively disturbed the formation of C center. Furthermore, the PL intensity seems to be scaled to the intensity of the signal C. This finding indicates that the C center plays an important role in the host excited PL of GaAs:Er,O. [ABSTRACT FROM AUTHOR]

Electron spin resonance (ESR) measurements of GaAs:Er,O grown by organometallic vapor phase epitaxy have been performed at 9.49 GHz from 4.5 to 13 K. Several anisotropic ESR signals (A, B, C, and D) are observed, which is consistent with the previous reports. We reexamined the angular dependence and temperature dependence of the signals in detail. Our ESR results indicate that the direction of alignment of two oxygen atoms or two arsenic atoms for an Er-2O center deviates from the <110> direction in various ways, resulting in the various Er-2O centers. Our ESR results also indicate that the paramagnetic states of the Er centers in GaAs change to a singletlike nonmagnetic state below 8 K. The ESR measurements under illumination have been performed to investigate the effect of photoexcitation of the host. This result indicates that the energy transfer efficiency from the host to the B center is especially large. We found that the luminescent Er-2O center B and another Er-2O center C considerably differ in the coupling with the lattice. [ABSTRACT FROM AUTHOR]

Presents a study that investigated the donor-related deep electron traps in tellurium-doped Al[sub x] Ga{sub 1-x] Sb on gallium antinomy substrate by deep level transient spectroscopy, capacitance-voltage, photocapacitance and Hall-effect measurements. Experimental procedures; Results and discussion.