Growth of Si∕β-FeSi2∕Si double-heterostructures on Si(111) substrates by molecular-beam epitaxy and photoluminescence using time-resolved measurements

Highly [110]/[101]-oriented semiconducting iron disilicide beta-FeSi2 continuous films were grown on Si(111) by molecular-beam epitaxy (MBE) using a beta-FeSi2 epitaxial template formed by reactive deposition epitaxy. The optimum MBE growth temperature was determined to be about 750°C. At this temperature, the full width at half maximum beta-FeSi2(220)/(202) x-ray diffraction peak was at a minimum. Subsequent MBE overgrowth of an undoped Si layer was performed on the beta-FeSi2 at 500°C, resulting in the Si/beta-FeSi2/Si double heterostructure. After annealing the wafers at 800°C in Ar for 14 h, 1.55 µm photoluminescence (PL) was obtained at low temperatures. Time-resolved PL measurements elucidated that the luminescence originated from two sources, one with a short decay time (tau~10 ns) and the other with a long decay time (tau~100 ns). The short decay time was thought to be due to carrier recombination in beta-FeSi2, whereas the long decay time was due probably to a dislocation-related D1 line in Si