Ion-beam irradiation effect on solid-phase growth of β-FeSi2

Effects of Ar+ ion-beam irradiation on solid-phase growth of β-FeSi2 have been investigated. Fe View the MathML source structures were irradiated with View the MathML sourceView the MathML source at a temperature of 25°C (sample A) or 400°C (sample B), and subsequently annealed at 800°C. A reference was obtained after annealing without irradiation (sample C). X-ray diffraction results indicated that β-FeSi2 was formed after annealing at 800°C for View the MathML source, and the formation rate was the fastest for sample A and the slowest for sample C, i.e., A>B⪢C. However, Auger electron spectroscopy measurements showed that atomic mixing at Fe/Si interface before annealing was B>A⪢C. These results suggested that amorphization of Si substrate, in addition to atomic mixing, enhanced the solid-phase growth of β-FeSi2, which was confirmed experimentally. Moreover, a direct band gap of View the MathML source was observed for the sample with pre-amorphization by the Fourier-transform infrared (FT-IR) spectroscopy measurements. These enhancement effects were attributed to that the phase transition to β-FeSi2 was accelerated by atomic arrangement induced during annihilation of excess vacancies. These enhancement effects can be utilized for nano-fabrication of β-FeSi2 by using focused ion-beam irradiation.