High resolution transmission electron microscopy study of iron-silicide nanodot structures grown on faintly oxidized Si (111) surfaces

Epitaxial iron-silicide (α-FeSi2, ε-FeSi and β-FeSi2) nanodots were grown on Si(111) substrates with SiO2 ultrathin films by Fe deposition on Si nanodots. The nanodots were characterized in-situ by reflection high-energy electron diffraction and scanning tunneling microscopy, and ex-situ high resolution transmission electron microscopy (HRTEM). For the β-FeSi2 nanodots, the HRTEM images and the corresponding fast Fourier transform patterns analyses revealed that the coherent β-FeSi2 nanodots with a relation of β-FeSi2(110)/Si(111) had a compressive strain of ~ 0.8% in the [001]β-FeSi2 direction and a tensile strain of ~ 2.6% in the direction normal to (110)β-FeSi2 plane.