| Summary: | 碩士 === 國立中興大學 === 材料科學與工程學系所 === 97 === Iron silicide nanoparticles were grown on Si substrate by reactive deposition epitaxy at various temperatures. Fe thin films, 2 and 5 nm in thickness, were deposited on n-type and p-type Si substrates at 500-700 °C and were further annealed in situ at the same temperature for 10 min to 4 hr. The reactions of Fe and Si substrates, the structure properties of the silicide nanoparticle/Si substrate interfaces and optical properties of iron silicide nanoparticles were studied by SEM, AFM, TEM and PL analyses. The results show as follows. Type-B FeSi(CsCl) or γ-FeSi2 nanoparticles and a few of β-FeSi2 nanoparticles were formed at 500 ºC. Type-A and type-B γ-FeSi2, α-FeSi2 and β-FeSi2 nanoparticles coexisted in the samples that were deposited at 600 ºC. β-FeSi2 was transformation from γ-FeSi2. α-FeSi2 phase was predominant in the sample that was deposited at 700 ºC. Among these iron silicide nanoparticles, α-FeSi2 and β-FeSi2 nanoparticles tended to protrude out of the Si substrate and FeSi(CsCl) and γ-FeSi2 nanoparticles preferred to embed in the Si substrate.
From the results of PL analysis of the iron silicide precipitates formed in various processes on n-type and p-type Si substrates type, PL peaks at 1616 nm and 1656 nm are the emission due to impurities at interface at γ-FeSi2 nanoparticles/Si substrates. The broad peak at the range of 1300 nm to 1600 nm can be attributed to the intrinsic emission of semiconducting β-FeSi2 with P dopant. In addition, the shape and size of the nanoparticles altered and reduced, respectively, with the increase of the annealing time, which caused that the intensity of PL peaks increased.
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