Coherent Hole Transport in Selective Area Grown Ge Nanowire Networks

Area of Science:

• Quantum computing
• Condensed matter physics
• Nanotechnology

Background:

• Germanium nanowires are a realistic platform for spin qubit logic in quantum computing.
• Their large spin-orbit coupling enables fast qubit operations.
• Nanowire geometry and orientation can mitigate charge noise and hyperfine interactions.

Purpose of the Study:

• To demonstrate a scalable synthesis and organization method for germanium nanowires on silicon substrates.
• To investigate the electronic transport properties of germanium nanowire networks.

Main Methods:

• Selective growth of germanium nanowire networks on nanopatterned silicon (100) substrates using metalorganic vapor phase epitaxy.
• Low-temperature electronic transport measurements on nanowire Hall bar devices.
• Magneto transport measurements to probe quantum phenomena.

Main Results:

• Achieved high hole doping (∼10^18 cm^-3) and a mean free path (∼10 nm) in germanium nanowires.
• Observed quantum diffusive transport, universal conductance fluctuations, and weak antilocalization.
• Determined coherence length (∼100 nm) and spin-orbit length (∼10 nm).

Conclusions:

• The developed method enables scalable synthesis and organization of germanium nanowires for quantum applications.
• The observed transport phenomena confirm the potential of germanium nanowires for robust spin qubit operation.
• Further research can leverage these findings for the development of practical quantum computing hardware.