Ion Beam Mixing at Crystalline and Amorphous Fe/Si Interfaces

Abstract

This study presents an optimization and characterization of amorphous Iron Disilicide (a-FeSi 2) 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 200keV. 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-FeSi 2 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 ~0.90eV have been observed for those samples with the highest levels of silicidation, with optical absorption coefficients of ~10 4 cm-1. Therefore this method of fabrication has been shown to produce a-FeSi 2 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.