X-ray and optical characterization of beta-FeSi2 layers formed by pulsed ion-beam treatment

beta -FeSi2 layers were formed on Si by means of high-dose Fe+ implantation into Sit 100) at 300 K followed by nanosecond pulsed ion-beam treatment (P IBT) of the implanted layers. It is shown that PIBT leads to the formation of a mixture of two phases (FeSi and beta -FeSi2) with a strained state of the silicide crystal lattice. Subsequent short-duration thermal annealing a t 800 degreesC for 20 min results in a decrease of the lattice strains and in the complete transformation of the FeSi phase into the beta -FeSi2 phase , with the production of a highly textured layer with the [110] orientation . The results of the optical absorption measurements indicate the formation of a direct band gap structure with the optical gap E-g similar to 0.83 eV and the Urbach tail width E-0 similar to 0.22 eV.