Epitaxial growth of ferromagnetic semiconductor Ga1Â -Â xMnxAs film on Ge(001) substrate

We have grown a high-quality epitaxial Ga1 - xMnxAs (x = 0.06) film on a Ge(001) substrate without a buffer layer by using low-temperature molecular beam epitaxy. The transmission electron microscope image revealed an atomically flat Ga1 - xMnxAs(001)/Ge(001) interface as well as the absence of precipitates such as MnAs. The film exhibited clear hysteresis in the magnetization curves at low temperatures, indicating a ferromagnetic Ga1 - xMnxAs film. The Curie temperature of the Ga1 - xMnxAs/Ge sample was strongly enhanced by post-growth annealing, which was similar to the Ga1 - xMnxAs/GaAs reference sample. Such results will accelerate the integration of III-Mn-V ferromagnetic semiconductors into Ge-based spintronics devices.