Atomically-controlled Fe3Si/Ge hybrid structures for group-IV-semiconductor spin-transistor application

Recent our progress in low temperature molecular beam epitaxy of magnetic silicide (Fe₃Si) on group-IV-semiconductor (Ge) was reviewed. By optimizing beam flux ratio (Fe:Si=3:1) and growth temperature (130°C), a high quality hybrid structure, i.e., DO₃-type Fe₃Si on Ge with an atomically flat interface, was achieved. Excellent magnetic properties with a small coercivity (0.8 Oe) and electrical properties with Schottky barrier height of 0.56 eV were obtained. The ratio of the on-current to the off-current of Schottky diode was the order of 10⁴. These results will be a powerful tool to open up group-IV-semiconductor spin-transistors, consisting of Ge channel with high mobility and Fe₃Si source/drain for spin-injection.