Ferromagnetic Mn 5Ge3C0.8 contacts on Ge: work function and specific contact resistivity

We report on the study of the electrical and magnetic properties of Mn 5Ge3C0.8 contacts deposited on highly doped n-Ge (1 0 0) as a potentially complementary metal-oxide-semiconductor (CMOS)-compatible material system for spin injection into Ge. Mn 5Ge3C0.8 is a ferromagnet with a Curie temperature of 445 K and with a resistivity that is comparable to highly doped Ge. We extract the work function of Mn5Ge3C0.8 from metal-oxide-semiconductor capacitance measurements and obtain a specific contact resistivity rC = 5.0 ω cm2 from transmission-line measurements. We discuss possible origins of the large specific contact resistivity of Mn5Ge3C0.8 on Ge.