Optimization and Characterisation of Amorphous Iron Disilicide formed by Ion Beam Mixing of Fe∕Si Multilayer Structures for Photovoltaic Applications

This study presents an optimization and characterization of amorphous Iron Disilicide (a‐FeSi2) synthesized using Ion Beam Mixing (IBM) of Fe∕Si multilayer structures. The layers were deposited using RF magnetron sputtering, and subsequently irradiated with Ar+ and Fe+ beams of 150 and 200 keV. Rutherford Back Scattering (RBS) analysis was used to determine the structure and level of silicidation of the samples. The nature of the band‐gap and the optical absorption coefficients were determined by optical transmission analysis. The results demonstrate that the synthesis of a‐FeSi2 can be achieved using this technique, with the total level of silicidation being highly dependant upon the initial structure configuration and beam parameters. Direct band‐gap energies of ∼0.90 eV have been observed for those samples with the highest levels of silicidation, with optical absorption coefficients of ∼ 104 cm−1. Therefore this method of fabrication has been shown to produce a‐FeSi2 layers without the need for post‐synthesis treatment, using established technologies without compromising the optical properties that make this material such a promising semiconductor for the photovoltaics market