| Summary: | 碩士 === 國立清華大學 === 材料科學工程學系 === 97 === In this study, FeSi nanowires were fabricated by chemical vapor deposition method. Beta-FeSi2 nanowires were deposited on Si substrate by applying FeCl3 as precursor at temperature ranged from 700 to 900 ℃. The structure of beta-FeSi2 nanowire was confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The surface morphology were analyzed by scanning electron microscopy (SEM). This study provide a stable and catalyst-free procedure for beta-FeSi2 nanowire at temperature ranged from 700 to 900 ℃.
Metal Silicides are characterized by their high thermal stability and better resistance against oxidation than pure metals. Most of them are metallic and have low resistivity. Exactly metallic silicides were first employed for interconnections, gate in MOS structures, ohmic contacts, and Scotty barriers.
From the Fe-Si phase diagram, numerous specific phase has been identified in both metal-rich and silicon-rich regions. They clearly demonstrate which definitely shows the complexity of the system with different chemical compositions such as Fe3Si, FeSi2, Fe5Si3, FeSi…etc. In addition, even with the same stoichiometry samples might possess diverse properties due to their lattice and electronic structure.
Even if the growth mechanism is not yet fully recognized, it was reported that morphology of one dimension FeSi nanowires [1] and FeSi spiral structure [2] could be acquired by chemical vapor deposition (CVD) under certain condition with careful control of temperature, pressure and the flow rate of carrier gas.
The fantastic features of beta-FeSi2 were thoroughly investigated. The theoretical prediction and experimental results show that beta-FeSi2 has a high optical coefficient as well as a direct band gap of ~ 0.85 eV [3] , which corresponding to the optical wavelength of 1.5 μm. As a result, we can mixing beta-FeSi2 with other silicides with various gaps integrated on a single silicon chip and offers potential applications in areas, such as infrared light detectors, opto-electric devices, and photovoltaics.
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