We have determined the schematic phase diagram in detail with high reliability for Fe silicides grown by solid phase epitaxy ͑SPE͒ on a Si͑111͒7 ϫ 7 surface at wide Fe coverage ͑0.2-56 monolayers͒ and subsequent annealing temperatures from 300 to 800°C. In the SPE growth, ␦-7 ϫ 7, 1 ϫ 1, bcc-Fe͑111͒1 ϫ 1, 2 ϫ 2, c͑8 ϫ 4͒, 3D-2 ϫ 2 ͑␣-FeSi 2 ͒, ͱ 3 ϫ ͱ 3-R30°, ␤-FeSi 2 , and fine polycrystalline phases are formed on the Si͑111͒ surface depending on Fe coverage and annealing temperature. We have characterized the surface periodic structures and morphologies of all the above Fe silicide phases using low-energy electron diffraction and scanning tunneling microscopy. Reflection high-energy electron diffraction also has been used to determine three-dimensional structures. Based on the overall view regarding the formations and changes of Fe silicide phases on a Si͑111͒ surface, we discuss the growth mechanisms.

The atomic structure of thin iron silicide film, grown epitaxially on the Si(111) surface, has been analyzed by means of the three-dimensional RHEED Patterson function analysis. The iron-silicide-terminated surface with (2 × 2) periodicity has been prepared by a solidphase epitaxy method. 2 ML of Fe were deposited on the Si(111)-(7 × 7) surface and annealed at 500 • C. Three-dimensional Patterson function was calculated from series of φ-scanned RHEED intensity distributions converted to the k-space. The resulting model of γ-FeSi2 structure consists of two silicide layers faulted to each other with three relaxed Si adatoms above the H3 site.PACS : 61.14.Hg, 68.55.-a

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