Interface Structure of an Epitaxial Iron Silicide on Si(111) Studied with X-Ray Diffraction

Abstract

Atomic structures of iron-silicide ultra-thin films epitaxial grown on Si(111) were investigated by x-ray crystaltruncation-rod scattering measurements. Two films, each of them respectively exhibited 1×1 and 2×2 periodicities in ultra high vacuum, were measured with the x-ray diffraction under ambient air. Both of the films showed essentially the same Laue peaks. The Laue peaks directly indicate that both films have the CsCl-type (so-called c-FeSi) structure whose stacking orientation is rotated by 180 • with respect to the substrate. Quantitative structural analysis, which includes degree of the film roughness as fit parameters, reveals that the interfacial Fe atom is 8-fold coordinated to Si atoms (so-called B8 model). The determined interlayer spacing in the silicide film and the Fe-Si bond length at the interface are respectively ∼6 % and ∼9 % larger than those in the hypothetical c-FeSi.

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

“…Then the method was applied to the analysis of an iron silicide thin film on the Si(111) surface. The result indicated that the iron silicide of Si(111)-2×2-Fe is of CsCl B8-type, consistent with the analysis done by using the least squares fitting [16].…”

“…X-ray intensities were observed along the 00, 10, and 01 rods in atmosphere. Details of the experimental results and analyses using the least squares fitting are described elsewhere [16]. The results support the CsCl-type structure for both samples.…”

Endotaxially stabilized B2-FeSi nanodots in Si (100) via ion beam co-sputtering

“…2,8 Interest in B2-FeSi increased somewhat recently, however, with the confirmation of antiferromagnetic spin ordering, with potential applications in high-density magnetic data storage and spintronics. 9 While an uncommon phase, a review of the literature does yield several theoretical [10][11][12] and experimental [13][14][15][16] works. These previous studies have reported macroscopic high pressure transitions to the B2 phase at >24 GPa, 14 which is of relevance to the study of geological processes in the Earth's mantle; or thin films and multilayers stabilized epitaxially on carefully prepared surfaces.…”

“…These previous studies have reported macroscopic high pressure transitions to the B2 phase at >24 GPa, 14 which is of relevance to the study of geological processes in the Earth's mantle; or thin films and multilayers stabilized epitaxially on carefully prepared surfaces. 13,16 The topic of the current letter is the synthesis and characterization of nanodots of B2-FeSi in Si(100) substrates, which have not been reported previously. Samples were prepared in a UHV system (Mantis Deposition Ltd, UK) at ambient temperature, using an Ar þ ion source (MATS) for simultaneous substrate ion etching and iron deposition, similarly to Zhang et al, 18 until a surface coverage of approximately 1 nm of iron was obtained.…”

Formation and properties of thin films of iron silicides on Si(111) Surface: Ab initio simulation

“…The results of previous experimental investigations [2][3][4][5][6][7][8][9] showed that the deposition of 2-3 monolayers (ML) of iron onto a Si(111) surface, followed by the annealing of obtained structures at 300-350°C, leads to a change in the surface silicide reconstruction from 1 × 1 to 2 × 2 and the formation of a CsCl type struc ture. The subsequent annealing retains the 2 × 2 peri odicity.…”