Ferromagnetic germanide in Ge nanowire transistors for spintronics application

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Exploring spintronics applications requires ferromagnetic materials with high Curie temperatures and high-quality interfaces with germanium.
• Germanium (Ge) nanowires are promising for future electronic devices.

Purpose of the Study:

• To report the formation and characterization of Mn(5)Ge(3)/Ge/Mn(5)Ge(3) nanowire heterostructures for spintronics.
• To investigate the properties of the interface between Mn(5)Ge(3) and Ge.
• To evaluate the performance of Ge nanowire transistors utilizing these heterostructures.

Main Methods:

• Fabrication of Mn(5)Ge(3)/Ge/Mn(5)Ge(3) heterostructures via solid-state reaction and thermal annealing of Ge nanowires with Mn contacts.
• Characterization of the interface quality using techniques sensitive to atomic structure and lattice mismatch.
• Electrical characterization including temperature-dependent I-V measurements and field-effect transistor performance evaluation.

Main Results:

• Formation of room-temperature ferromagnetic Mn(5)Ge(3) on single-crystalline Ge nanowires.
• Observation of an atomically clean interface between Mn(5)Ge(3) and Ge with a 10.6% lattice mismatch.
• Determination of a Schottky barrier height of 0.25 eV for Mn(5)Ge(3) on p-type Ge.
• Achieved high-performance p-type Ge nanowire transistors with a current on/off ratio of ~10^5 and hole mobility of 150-200 cm^2/(V s).
• Observed clear resistance transition near the Curie temperature (~300 K) of Mn(5)Ge(3).

Conclusions:

• Mn(5)Ge(3) serves as a high-quality, room-temperature ferromagnetic contact for Ge.
• These findings represent a significant advancement towards electrical spin injection into Ge nanowires.
• The developed heterostructures hold promise for realizing high-efficiency spintronic devices for room-temperature applications.