FORMATION OF EPITAXIAL 1-LESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-1) SILICIDES ON SI(111)(X (0)

Epitaxial Fe3-xSi1+x films have been grown on Si(111) by codeposition at room temperature. Their structural and electronic properties have b een investigated by means of low-energy electron diffraction (LEED), x -ray photoelectron diffraction (XPD), and x-ray photoemission spectros copy (XPS). These films, with compositions ranging from Fe3Si to FeSi, exhibit a (1X1) LEED pattern. Both XPD and core level binding energy measurements indicate that single Fe3-xSi1-x phases (with 0<x<1), with out bulk counterpart, can be stabilized by epitaxy on Si(111). The XPD experiment clearly shows that these Fe3-xSi1+x (0 less than or equal to x less than or equal to 1) films adopt the same cubic structure. Fu rthermore, the Si 2p, Fe 2p(3/2), and Fe 3s core levels are slightly s hifted to higher binding energies resulting from chemical effects and differences in local coordination when going from Fe3Si (DO3) to FeSi (CsCl). Multiplet splittings Delta E(3s) are observed in Fe 3s core-le vel XPS spectra for all Fe3-xSi1+x compounds except the FeSi (CsCl) on e. (C) 1995 American Institute of Physics.