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

Abstract

Highly [110]∕[101]-oriented semiconducting iron disilicide β-FeSi2 continuous films were grown on Si(111) by molecular-beam epitaxy (MBE) using a β-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 β-FeSi2(220)∕(202) x-ray diffraction peak was at a minimum. Subsequent MBE overgrowth of an undoped Si layer was performed on the β-FeSi2 at 500°C, resulting in the Si∕β-FeSi2∕Si double heterostructure. After annealing the wafers at 800°C in Ar for 14h, 1.55μm 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 (τ∼10ns) and the other with a long decay time (τ∼100ns). The short decay time was thought to be due to carrier recombination in β-FeSi2, whereas the long decay time was due probably to a dislocation-related D1 line in Si.