Epitaxial growth of Fe(001) onCoSi2(001)/Si(001)surfaces: Structural and electronic properties

Abstract

Ultrathin Fe films, in the thickness range 0\char21{}40 monolayers (ML), have been grown on Si(001) by molecular-beam epitaxy and characterized by low-energy electron diffraction, inelastic medium-energy electron diffraction, x-ray photoelectron spectroscopy, angular-resolved ultraviolet spectroscopy, x-ray photoelectron diffraction, ion scattering spectroscopy, and transmission electron microscopy. For Fe depositions onto Si(001) at room temperature, a disordered layer is obtained due to a high degree of intermixing between the Fe deposit and the Si substrate. Successful epitaxial growth of Fe at room temperature is achieved by use of a thin (\ensuremath{\sim}10 \AA{}) ${\mathrm{CoSi}}_{2}$ silicide interlayer epitaxially grown on the Si(001) substrate prior to the Fe deposition, which prevents the intermixing of the Si substrate atoms into the Fe overlayer. Below a coverage of \ensuremath{\sim}2 ML, a reacted ordered iron-rich phase forms at the surface. At higher coverages, there is growth of an epitaxial essentially body-centered cubic (bcc) Fe(001) overlayer with the orientational relationships $\mathrm{Fe}(001)\mathrm{〈}001\mathrm{〉}\ensuremath{\parallel}{\mathrm{CoSi}}_{2}(001)\mathrm{〈}001\mathrm{〉}\ensuremath{\parallel}\mathrm{Si}(001)\mathrm{〈}001\mathrm{〉}.$ Finally, a well-ordered ${\mathrm{F}\mathrm{e}/\mathrm{C}\mathrm{o}\mathrm{S}\mathrm{i}}_{2}$ interface is formed even at room temperature.