Formation of $\beta$-FeSi2-xGex by Ge-Segregation-Controlled Solid-Phase Growth of [a-Si/a-FeSiGe]n Multilayered Structure

概要

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The solid-phase growth of [a-Si/a-Fe0.4Si0.5Ge0.1]n ($n=1$, 2, 4; total thickness: 500 nm) multilayered structures has been investigated. After annealing at 700°C, [a-SiGe/polycrystalline $\beta$-FeSi2-xGex]n ($x=0.5$, 0.4, 0.2 for $n=1$, 2, 4, respectively) multilayered structures were formed. From the analysis of X-ray diffraction spectra, it was found that the lattice constants of $\beta$-FeSi1.5Ge0.5 changed from those of relaxed $\beta$-FeSi2 by 0.4–0.5%. The change decreased with increasing $n$, which was due to the segregation of Ge atoms from the a-Fe0.4Si0.5Ge0.1 layers to the a-Si layers becoming larger with increasing $n$. After annealing at 800°C, Ge atoms were completely swept out from the $\beta$-FeSi2-xGex lattice. In addition, the agglomeration of $\beta$-FeSi2 occurred, and nanocrystals of relaxed $\beta$-FeSi2 and c-Si0.7Ge0.3 were formed. This technique for the formation of $\beta$-FeSi2-xGex is expected to be useful for energy gap modulation for advanced optoelectrical devices.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2004-04-15