Pulsed ion-beam synthesis of β-FeSi2 precipitate layers in Si(100)

Semiconducting iron disilicide (beta-FeSi2) precipitate layers were synthesized by means of Fe+ implantation into Si(100) at an energy of 40 keV and a dose of 1 X 10(16) cm(-2) followed by nanosecond pulsed ion-beam treatment of the implanted Si layers. Glancing incidence x-ray diffraction (GIXRD) and atomic force microscopy (AFM) were employed for the structural characterization, and optical absorption and photoluminescence (PL) spectroscopies were used for the optical characterization of the precipitate layers formed. The GIXRD results indicate the formation of oriented beta-FeSi2, precipitates surrounded by a polycrystalline Si matrix. AFM data show the precipitate sizes to be in the range of 25-90 nm. The results of measuring the optical absorption indicate that the formed precipitates have a direct-band structure with an energy gap of 0.83 eV. It is shown that the 1.5 mum PL signal of beta-FeSi2 precipitates is observed up to a temperature of 210 K and does not saturate up to the pump power of 250 mW.