Characterization of half-metallic L2₁-phase Co₂FeSi full-Heusler alloy films formed by rapid thermal annealing

The authors developed a preparation technique of Co_2FeSi full-Heusler alloy films with the L2_1-ordered structure on silicon-on-insulator (SOI) substrates, employing rapid thermal annealing (RTA). The Co_2FeSi full-Heusler alloy films were successfully formed by RTA-induced silicidation reaction between an ultrathin SOI (001) layer and Fe/Co layers deposited on it. The highly (110)-oriented L2_1-phase polycrystalline full-Heusler alloy films were obtained at the RTA temperature of 700 C. Crystallographic and magnetic properties of the RTA-formed full-Heusler alloy films were qualitatively the same as those of bulk full-Heusler alloy. This technique is compatible with metal source/drain formation process in advanced CMOS technology and would be applicable to the fabrication of the half-metallic source/drain of MOSFET type of spin transistors.