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We have epitaxially grown Si/ ␤-FeSi 2 /Si ͑SFS͒ structures with ␤-FeSi 2 particles on Si͑001͒, and SFS structures with ␤-FeSi 2 continuous films on both Si͑001͒ and Si͑111͒ substrates by molecular-beam epitaxy. All the samples exhibited the same photoluminescence ͑PL͒ peak wavelength of approximately 1.54 m at low temperatures. However, the PL decay times for the 1.54 m emission were different, showing that the luminescence originated from different sources. The decay curves of the SFS structures with ␤-FeSi 2 continuous films were fitted assuming a two-component model, with a short decay time ͑ ϳ 10 ns͒ and a long decay time ͑ ϳ 100 ns͒, regardless of substrate surface orientation. The short decay time was comparable to that obtained in the SFS structure with ␤-FeSi 2 particles. The short decay time was due to carrier recombination in ␤-FeSi 2 , whereas the long decay time was probably due to a defect-related D1 line in Si. We obtained 1.6 m electroluminescence ͑EL͒ at a low current density of 2 A / cm 2 up to around room temperature. The temperature dependence of the EL peak energy of the SFS diodes with ␤-FeSi 2 particles can be fitted well by the semiempirical Varshni's law. However, EL peak positions of the SFS diodes with the ␤-FeSi 2 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.

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We fabricated single-, double-and triple-layered -FeSi 2 -particles structure on Si(001) substrates by reactive deposition epitaxy (RDE) for -FeSi 2 and by molecular beam epitaxy (MBE) for Si, and realized electroluminescence (EL) at 310 K. Photoluminescence (PL) measurements revealed that the 77 K PL intensity of -FeSi 2 increased almost proportionally with the number of -FeSi 2 -particles/Si layers. It was also found that the multilayered structure enhanced the EL intensity of -FeSi 2 particularly at low temperatures.

Ferromagnetic Fe3Si/CaF2 hybrid structures were epitaxially grown on Si(111) by molecular beam epitaxy. When Si and Fe were directly deposited on the Si substrate, it was difficult to prevent inclusion of FeSi in the grown films. This problem was overcome by forming a CaF2 epitaxial film on Si(111) first, followed by codeposition of Si and Fe to form Fe3Si. Fe3Si films were epitaxially grown on the CaF2 at 400°C. A distinct square-like hysteresis loop was observed at room temperature in the magnetic field dependence of Kerr rotation.