Formation of β-FeSi2 NDs by SiH4-exposure to Fe-NDs

We have demonstrated formation of β-FeSi2 nanodots (NDs) with an areal density as high as ~1011 cm-2 on SiO2 by exposing Fe–NDs to SiH4 at 400oC and characterized their room–temperature light–emission properties. After the SiH4–exposure even at 1.0 Pa for 60 sec, stable photoluminescence (PL) signals, being characteristic of the semiconducting phase as β–FeSi2, were observed in the energy region from 0.7 to 0.85 eV. With an increase in the amount of SiH4 exposure from 60 to 600 Pa·sec, PL intensity increased by a factor of ~13. Note that, further increase in the amount of SiH4 over 600 Pa·sec, the PL intensity is weakened slightly. The observed decrease in the PL intensity is attributable to selective growth of Si onto the NDs after the formation of β–FeSi2 phase.