Catalytic growth of α-FeSi2 and silicon nanowires

Via vaporization of Fe and Si powders mixed with a molar ratio of 1:1, α-FeSi2 nanowires were synthesized on one Si wafer, where the temperature is higher than 950 °C and Fe supply is enough, and meantime Si nanowires were obtained on the other Si wafer, where the temperature is lower than 500 °C and Fe atoms are much less than Si atoms in vapor. The two kinds of nanowires have diameters of 40-80 nm and lengths of 3-10 μm. Their shapes, crystallinity, and compositions are studied in terms of field emission scanning electron microscopy, X-ray diffraction spectra, and energy dispersive X-ray spectroscopy. From the obtained experimental results, we explain the growth mechanism of the two kinds of nanowires using the vapor-liquid-solid growth model. Two important conditions, high temperatures and enough Fe supply, are emphasized for syntheses of the α-FeSi2 nanowires.