Direct-Write Printing of Josephson Junctions in a Scanning Electron Microscope

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Josephson junctions are fundamental components in superconducting electronics, crucial for applications like precision metrology and quantum computing.
• Conventional fabrication of Josephson junctions is complex, resource-intensive, and involves multistep processes like lithography and wet-processing, limiting their widespread application.

Purpose of the Study:

• To introduce a fully additive, direct-write approach for fabricating Josephson junctions.
• To demonstrate a method compatible with various applications, bypassing traditional nanofabrication limitations.

Main Methods:

• Utilized electron-beam-induced deposition (EBID) of tungsten carbide to create Josephson junctions.
• Employed a scanning electron microscope for direct-write fabrication, enabling substrate-conformal device printing in minutes without post-processing.
• Leveraged EBID-tunable material properties to create proximity junctions with superconducting electrodes and metallic weak links in a single step.

Main Results:

• Successfully fabricated Josephson junctions entirely through EBID of tungsten carbide.
• Demonstrated the ability to tailor Josephson coupling by controlling EBID parameters.
• Verified Josephson behavior through microwave-induced Shapiro response and field-dependent transport measurements.

Conclusions:

• The developed additive direct-write approach offers a versatile, nondestructive, and efficient alternative to conventional Josephson junction nanofabrication.
• This method can be expanded for printing 3D superconducting sensor arrays and quantum networks, advancing superconducting electronics.
• The technique simplifies the fabrication process, making Josephson junction technology more accessible for diverse applications.