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

The authors developed a preparation technique of Co2FeSi full-Heusler alloy thin films with the L21-ordered structure on silicon-on-insulator (SOI) substrates, employing rapid thermal annealing (RTA). The Co2FeSi 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 L21-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. The proposed technique is compatible with metal source∕drain formation process in advanced complementary metal-oxide semiconductor technology and would be applicable to the fabrication of the half-metallic source∕drain of metal-oxide-semiconductor field-effect transistor type of spin transistors.