Epitaxial growth of Fe-Si compounds on the silicon (111) face

Abstract

In a molecular-beam-epitaxy (MBE) chamber, epitaxial growth of all the silicides existing in the lowtemperature portion of the iron-silicon phase diagram Ie.g., bcc Fe {+Si),Fesi, and the semiconducting silicide P-FeSi2] was achieved on the (111)face of silicon by deposition of pure iron onto a heated silicon substrate. The epitaxial growth has been characterized by means of in situ reAection high-energy electron diffraction (RHEED), ultraviolet photoemission spectroscopy, and x-ray photoemission spectroscopy. A strained phase, s-FeSi2, has been clearly identified and shown to be metallic. This phase could be stabilized by the anisotropic elastic field induced by the epitaxy on the silicon (111)face which prevents a solid-state Jahn-Teller effect from distorting the cubic FeSi, structure and opening the gap. Also during the growth, dynamical transitions between the different epitaxial phases have been observed at definite thicknesses (typically in the range 10 -20 A): (i) At the temperature of the silicon substrate T =350'C, strained s-Fesi2~Fesi; (ii) at T =400 C, strained s-Fesiz~P-FeSi2. In our work such dynamical transitions are experimentally observed in situ during the growth. This shows that the use of a MBE chamber and in situ RHEED are very powerful techniques for studying and controlling metallurgical transformations on nanorneter scale in real time. We interpret these dynamical transitions as being due to the combination of two effects: a change in the silicon atomic flux coming from the silicon substrate to the surface and the relaxation of the strained phase.

Iron silicide formation at different layers of (Fe/Si)3 multilayered structures determined by conversion electron Mössbauer spectroscopy

“…According to previous works on the Fe-Si interfaces, 3,5,11,12,15,[27][28][29][30][31] these compounds would have a magnetic Fe 1Àx Si x alloy, and a paramagnetic silicide. The non-stoichiometric c-Fe 1Àx Si phase (0 x 0.5) has been proposed as that paramagnetic compound.…”

“…The non-stoichiometric c-Fe 1Àx Si phase (0 x 0.5) has been proposed as that paramagnetic compound. 11,27,29,30,[32][33][34][35] We focus our attention on the analysis of the paramagnetic component given by the doublets. The c-FeSi phase with the cubic CsCl structure should show a singlet.…”

Effect of Si/Fe Composition, Substrate Temperature, and Substrate Orientation on the Structure and Magnetic Properties of Fe-Si Alloy Film

“…(4) Figure 26 shows the anisotropy energy, Ea, as a function of θM calculated by using the equation (4 17) . However, the films prepared in the present study show nearly isotropic in-plane magnetic anisotropies.…”

“…There are some reports on the investigations concerning the relationships of Si/Fe composition and crystallographic orientation with respect to the magnetic properties by using bulk Fe-Si single-crystal materials 3,4) . However, it is not easy to prepare bulk crystal samples systematically varying the Si composition or the crystallographic orientation.…”

Effects of source materials on fabrication of β-FeSi2 thin films by RDE method

“…Thus, β-FeSi2 is expected to be a promising material for near-infrared light emitter, detector or solar cells. In terms of thin film growth, the reactive deposition epitaxial (RDE) growth, which deposit pure Fe onto heated Si substrate so that the reaction of deposited Fe and Si supplied from substrate proceed, was studied actively in the early researches on β-FeSi2 thin films growth [5][6][7]. However, the RDE method is not appropriate to fabricate the thickness of films greater than 100 nm due to the epitaxial β-FeSi2 film that easily aggregates into β-FeSi2 islands and the interface between the grown β-FeSi2 islands and Si substrate becomes relatively rough.…”