To explore spintronics app
lications for Ge nanowire heterostructures formed by thermal annea
ling, it is critical to develop a ferromagnetic germanide with high Curie temperature and take advantage of the high-qua
lity interface between Ge and the formed ferromagnetic germanide. In this work, we report, for the first time, the formation and characterization of Mn
5Ge
3/Ge/Mn
5Ge
3 nanowire transistors, in which the room-temperature ferromagnetic germanide was found through the so
lid-state reaction between a single-crystal
line Ge nanowire and Mn contact pads upon thermal annea
ling. The atomically clean interface between Mn
5Ge
3 and Ge with a relatively small lattice mismatch of 10.6% indicates that Mn
5Ge
3 is a high-qua
lity ferromagnetic contact to Ge. Temperature-dependent
I鈥?i>V measurements on the Mn
5Ge
3/Ge/Mn
5Ge
3 nanowire heterostructure reveal a Schottky barrier height of 0.25 eV for the Mn
5Ge
3 contact to
p-type Ge. The Ge nanowire field-effect transistors built on the Mn
5Ge
3/Ge/Mn
5Ge
3 heterostructure exhibit a high-performance
p-type behavior with a current on/off ratio close to 10
5, and a hole mobi
lity of 150鈥?00 cm
2/(V s). Temperature-dependent resistance of a fully germanided Mn
5Ge
3 nanowire shows a clear transition behavior near the Curie temperature of Mn
5Ge
3 at about 300 K. Our findings of the high-qua
lity room-temperature ferromagnetic Mn
5Ge
3 contact represent a promising step toward electrical spin injection into Ge nanowires and thus the rea
lization of high-efficiency spintronic devices for room-temperature app
lications.
Keywords:
germanium nanowire heterostructure; Mn5Ge3; manganese germanide; atomically clean interface; spin injection