Structural and Magnetic Properties of CoFe/Sn-Doped Ge/Co2FeSi for Vertical Spin-Valve Devices on Si

For the vertically stacked semiconductor spintronic devices on Si, we develop a low-temperature growth technique of an epitaxial Ge layer with Sn doping on a Co-based Heusler alloy, Co
2
FeSi grown on Fe3Si/Si(111). Thanks to the Sn doping, the growth temperature for the Ge layer is significantly reduced down to ~110 °C, resulting in the suppression of the atomic interdiffusion between Ge and Co
2
FeSi. The chemically abrupt interface leads to the improvement of magnetic properties of the all-epitaxial CoFe/Ge/Co
2
FeSi/Fe
3
Si/Si(111) structure. This study will pave a way for high-performance Ge-based spintronics devices on Si.