Homogeneous surface iron silicide formation on Si(111): Thec(8×4)phase

Abstract

The early stages of iron silicide formation on Si͑111͒ were studied by scanning tunneling microscopy ͑STM͒, low-energy electron diffraction, and Auger electron spectroscopy. While the initial iron interaction with Si͑111͒ in the submonolayer regime gives rise to inhomogeneous island nucleation, deposition of 1.5 monolayers ͑ML͒ iron at room temperature and subsequent annealing at 550-600°C leads to a flat and homogeneous film with c(8ϫ4) surface periodicity. This c(8ϫ4) surface reconstruction is linked to a definite film thickness and thus seems to be stabilized directly through the interface. The film is terminated by a layer of adatoms whose lateral positions form a (2ϫ2) periodic lattice. At negative tip bias voltages, STM images show an alternating arrangement of darker and brighter adatoms corresponding to the c(8ϫ4) supercell. While the (2ϫ2)-periodic adatom arrangement develops in a wide temperature regime ͑450-600°C) and also for thicker films, the long range ordered c(8ϫ4) structure can be observed only for 1-2 ML Fe coverage and after high temperature annealing at about 600°C. Then single c(8ϫ4) domains can extend to diameters of several hundred nanometers. The atomic structure of the new phase can be derived from a CsCl (B2) structure, and a number of structural details are elucidated on the course towards the development of a complete structural model.

Investigation of Magnetic Dead Layer on Iron Silicide Surfaces

“…The investigation of the interfacial MDL for ultrathin Fe films on iron silicides and Si(111)-7×7 surfaces plays an important role for the heterojunction. As previously reported [30,31], the high-quality epitaxial ultrathin iron silicides can be obtained on Si(111). These iron silicides are thermally stable, and could be better candidates for the suppression of the interfacial MDL of Fe-Si alloy.…”

“…Ultrathin iron silicides were prepared on Si(111) surface in the same way as previous reports [30,31]. 1.7 ML Fe was deposited on Si(111) at RT, which was subsequently annealed.…”

Study of the Interface Structure of Epitaxial Ultra-Thin Film by an X-Ray Holographic Imaging Method

“…In this work we use only the result obtained for Si(111)-2×2-Fe. Since the fractional order reflections were not observed for Si(111)-2×2-Fe, the 2×2 periodicity is considered due to Si adatoms on the film, and is lost in the atmosphere [11]. The observed intensities along the 00 rod are reproduced in Fig.…”

“…In the region of a few monolayer deposition, thin films with 1×1, 2×2 and c(8×4) periodicity, observed by LEED, RHEED, STM etc., are fabricated almost separately. For the structure of those films, cubic CsCl-type, CaF 2 -type, and defect CsCl-type structures are proposed [9][10][11][12][13].…”

Interplay of growth mode and thermally induced spin accumulation in epitaxialAl/Co2TiSi/AlandAl/Co2TiGe/Alcontacts

“…[3][4][5][6][7] As an alternative one could use a light sp metal such as Al as a contact layer between Si and the ferromagnet. Ohmic contacts between Si and Al are well-studied and form a standard component in Si device technology.…”