Solid-phase growth of β-FeSi2 in thick Fe film on Si(111) substrates

We prepared β-FeSi2 films from Si(111) surfaces deposited with Fe of thicknesses of less than 150 nm by annealing in an ultrahigh vacuum environment. Reflection high-energy electron diffraction (RHEED) indicated that the surface crystallinity changed from body-centered-cubic Fe to non-crystallized Si by way of β-FeSi2 during the solid phase growth. The generation of β-FeSi2 was confirmed not only by RHEED but also by Raman spectroscopy. Although scanning electron microscope observations indicated that some of the initially deposited Fe remained unreacted on the β-FeSi2 surface after the solid phase growth, we found that it can be selectively removed with FeCl3 solution. We confirmed using X-ray photoelectron spectroscopy that β-FeSi2 films with a thickness of 15 nm were formed from 100-nm thick Fe-deposited Si(111) 7 × 7 surfaces. We discuss how to enhance the solid phase growth of β-FeSi2 on Si(111).

► We prepared β-FeSi2 films by annealing.
► The surface changed from the bcc-Fe to β-FeSi2 during the solid phase growth.
► This was confirmed by electron diffraction and Raman spectroscopy.
► We discuss how to enhance the solid phase growth of β-FeSi2.