Jpn. J. Appl. Phys. 46 (2007) pp. 5233-5237 |Previous Article| |Next Article| |Table of Contents|
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Growth of β-FeSi2 Layers on Si(100) Substrates by Exchange Reaction between Si and Molten Salts
Department of Materials Engineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
1Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
(Received March 26, 2007; accepted April 25, 2007; published online August 6, 2007)
The growth of β-FeSi2 layers on Si(100) substrates by a cation exchange reaction between Si and molten NaCl–KCl–FeCl2 salts, namely, 5Si(s)+2FeCl2(l)=2β-FeSi2(s)+SiCl4(g), has been investigated. A single-crystal Si(100) substrate was reacted with the molten salt at 1173 K for 1–64 h in Ar or He atmosphere. The grown layers were characterized by X-ray diffraction (XRD) measurement, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). When the FeCl2 concentration in molten salt was as low as 0.02 mol %, a β-FeSi2 single layer was obtained, although the double layer of FeSi/β-FeSi2 formed with a higher FeCl2 concentration of 0.1–1.0 mol %. The β-FeSi2 single layer grown at low FeCl2 concentration had a rough surface structure due to the decrease in driving force caused by the consumption of FeCl2 during the reaction. By annealing a flat double layer of FeSi/β-FeSi2 formed with a higher FeCl2 concentration where the driving force could be kept constant, a flat β-FeSi2 single layer was obtained on the Si(100) substrate.
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