High Density Iron Silicide Nanodots Formed by Ultrathin SiO2 Film Technique

We develop the epitaxial growth technique of ultrahigh density (>1012 cm-2) iron silicide nanodots (NDs) on Si substrates using ultrathin SiO2 films. This technique enables the ND formation of various kinds of iron silicides such as β-FeSi2 and Fe3Si. These NDs nanocontact with Si substrates through limited area of nanowindows in the ultrathin SiO2 films. Due to the nanocontact between NDs and Si substrates, heteroepitaxial growth of high quality NDs on Si substrate is successful. Absorption spectra of individual β-FeSi2 NDs show the property of the indirect transition semiconductor. However, the Si/β-FeSi2 NDs/Si structures exhibit strong photoluminescence near 0.8 eV.