Molecular beam epitaxy of the ferromagnetic silicide Fe 3Si on Ge and Si substrates was investigated in a wide temperature range (60–400 °C). Epitaxial growth of Fe 3Si layers was achieved on Ge (110), Ge (111), and Si (111) substrates. Especially, very low value (2.2%) of the minimum scattering yield in RBS measurements was obtained from Fe 3Si layers, which were grown on Ge (111) at low temperature (60–130 °C) under the stoichiometric condition (Fe:Si = 3:1). Transmission electron microscopy measurements confirmed the formation of DO3-type Fe 3Si and atomically flat interface between Fe 3Si and Ge (111). In addition, thermal stability of Fe 3Si was guaranteed up to 300 °C. Such high quality Fe 3Si on Ge (111) substrates can be employed to realize Ge channel spin transistors, which can be integrated with Si large-scale integrated circuits.