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We have epitaxially grown Si/β-FeSi2/Si (SFS) structures with β-FeSi2 particles on Si(001), and SFS structures with β-FeSi2 continuous films on both Si(001) and Si(111) substrates by molecular-beam epitaxy. All the samples exhibited the same photoluminescence (PL) peak wavelength of approximately 1.54 μm at low temperatures. However, the PL decay times for the 1.54 μm emission were different, showing that the luminescence originated from different sources. The decay curves of the SFS structures with β-FeSi2 continuous films were fitted assuming a two-component model, with a short decay time (τ∼10 ns) and a long decay time (τ∼100 ns), regardless of substrate surface orientation. The short decay time was comparable to that obtained in the SFS structure with β-FeSi2 particles. The short decay time was due to carrier recombination in β-FeSi2, whereas the long decay time was probably due to a defect-related D1 line in Si. We obtained 1.6 μm electroluminescence (EL) at a low current density of 2 A/cm2 up to around room temperature. The temperature dependence of the EL peak energy of the SFS diodes with β-FeSi2 particles can be fitted well by the semiempirical Varshni’s law. However, EL peak positions of the SFS diodes with the β-FeSi2 films showed anomalous temperature dependence; they shifted to a higher energy with increasing temperature, and then decreased. These results indicate that the EL emission originated from several transitions. [ABSTRACT FROM AUTHOR]

The photoluminescence (PL) decay times of Si/[beta]-Fe[Si.sub.2]/Si (SFS) double-heterostructure (DH) on both Si(001) and Si(111) substrates as well as those of SFS with [beta]-Fe[Si.sub.2] particles are examined. The results have shown that other luminescence such as D1 line has contributed to the electroluminescence (EL) from the SFS DH light emitting diodes (LEDs).

Abstract: The p-Si/p-β-FeSi2/p-Si/n-Si light-emitting diode (LED) was fabricated by molecular beam epitaxy (MBE) on Si(111) substrates. Compared to our previous p-Si/p-β-FeSi2/n-Si double heterostructures (DH) LED, the turn-on voltage in the current–voltage (I–V) characteristics increased by approximately 0.2 V, meaning that defect densities at around the p–n junction were reduced. However, Si-related EL (1.05 eV) became dominant unexpectedly, and thus EL of β-FeSi2 was suppressed accordingly. The origin of the luminescence is considered to be transitions via defect levels (1.05 eV) being due probably to Fe-B complex. [Copyright &y& Elsevier]

Abstract: We have fabricated single-, three- and five-layered Si/β-FeSi2/Si (SFS) double heterostructures (DH) on Si (001) substrates by reactive deposition epitaxy (RDE) for β-FeSi2 and by molecular beam epitaxy (MBE) for Si. Time-resolved photoluminescence (PL) measurements revealed that the luminescence at 1.54μm was composed of fast (16ns) and slow (150ns) components at 8K. These are thought to originate from β-FeSi2 and the defect-related D1 line in Si, respectively. 1.6μm electroluminescence (EL) was obtained at room temperature (RT) from the five-layered SFS DH for current densities above 20A/cm2. [Copyright &y& Elsevier]

Abstract: Si/β-FeSi2/Si (SFS) heterostructures were grown epitaxially on Si(001) by reactive deposition epitaxy (RDE) for β-FeSi2 and by molecular beam epitaxy (MBE) for Si. Distinct 1.54-μm photoluminescence was observed at 77 K for SFS with a β-FeSi2 thickness ranging from 5 to 10 nm. When the thickness of the β-FeSi2 layer was increased up to 40 nm, the PL intensity of β-FeSi2 decreased and the full-width at half maximum (FWHM) of the PL peak increased. Reflection high-energy electron diffraction observation revealed that the Si overlayer has a tendency to form polycrystalline structures with the increase of β-FeSi2 thickness. The degradation of PL was also observed for samples annealed at 900 °C. [Copyright &y& Elsevier]

Abstract: Ferromagnetic Fe3Si/CaF2/Si hybrid structures were grown epitaxially on Si(111) by molecular beam epitaxy. It was difficult to prevent inclusion of FeSi in the grown films in the case that Si and Fe were directly deposited on the Si substrate. This problem was overcome by inserting a CaF2 epitaxial film between the Fe3Si and Si substrate. Fe3Si films were grown epitaxially on the CaF2 at 400 °C. A distinct square-like hysteresis loop with coercive field of approximately 20 Oe was obtained in the magnetic field dependence of Kerr rotation at room temperature (RT). The saturation magnetization was approximately 550 emu/cm3 at RT by a super conducting quantum interference device magnetometer. [Copyright &y& Elsevier]

Several types of dialyzers with enhanced internal filtration have been introduced in order to increase solute clearance, especially in relatively larger molecular solutes. In these dialyzers, enhanced internal filtration increased convective transport of the solute in addition to diffusive transport. The internal filtration flow rate (QIF) has not, however, been measured in clinical situations, because none of monitoring techniques can measure this value. Herein, the QIF value was estimated during an experimental and an analytical study. Namely, we measured blood flow velocity in a cross-sectional plane of the dialyzer by pulse Doppler ultrasonography. An in vitro study with bovine blood was carried out to determine the local blood flow velocity profile with a newly designed probe slider that enables parallel movement of the probe along the dialyzer. Furthermore, an analytical model was newly introduced to calculate changes in flow rate and pressure of blood and dialysate streams and solute concentrations along the dialyzer. The QIF value could be estimated by a simulation analysis to the experimental data using the analytical model. [ABSTRACT FROM AUTHOR]