Shadowed versus Etched Superconductor-Semiconductor Junctions in Al/InAs Nanowires.

Area of Science:

• Quantum engineering
• Materials science
• Nanotechnology

Background:

• Hybrid semiconductor-superconductor nanowires are crucial for quantum devices.
• Current fabrication methods involve post-growth processing that can degrade performance.

Purpose of the Study:

• To present an in situ shadowing technique for superconductor deposition on nanowires.
• To compare the properties of superconductor-nanowire junctions fabricated by shadowing versus traditional etching.

Main Methods:

• In situ shadowing of aluminum (Al) superconductors onto semiconductor nanowires.
• Transmission electron microscopy (TEM) for structural analysis.
• Electrical transport measurements to assess electronic properties and electron mobility.

Main Results:

• Etching processes induce atomic-scale surface roughening on nanowires.
• This surface roughening negatively impacts electron mobility.
• Shadowing preserves surface integrity, leading to improved junction quality.

Conclusions:

• In situ shadowing is a viable alternative to etching for fabricating hybrid devices.
• The technique facilitates in situ fabrication and maintains high-quality quantum transport signatures.
• Advanced shadowing geometries are presented for future device integration.