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Tunnel junction and superconducting devices for ultra-high-performance cryogenic circuits and detectors

For the past 30 years, VTT has provided solutions and services for superconductor and tunnel junction device design and fabrication. We also help clients with small scale production.

Trilayer Josephson junctions

A niobium-aluminium/aluminium oxide-niobium Nb/Al-AlOx/Nb trilayer structure provides a robust technology for Josephson junction-based devices and circuits. Device operating temperature can range from 4 Kelvin down to sub-Kelvin temperatures, using up to three superconducting layers.

Advantages include:

  • wafer scale process
  • application-specific process flow
  • in-house expertise in design and fabrication
  • in-house testing capabilities
  • suspended structures.

Applications:

  • DC- and AC-SQUIDs
  • Josephson voltage standards
  • amplifiers for detector readout
  • x-ray detectors.

Al-Al2O3-based tunnel junctions

Tunnel junction technology with an Al bottom electrode and Al2O3 tunnel barrier is well suited for devices with low and/or high junction transparency. It supports both high device complexity and integration of additional passive elements.

Advantages include:

  • application-specific process flow
  • wafer-scale process
  • UV and E-beam capabilities
  • in-house device characterization
  • production scale-up capabilities.

Some applications include:

  • SQUID
  • phase Qubit
  • transmon Qubit
  • CBT
  • bolometers and coolers.

Suspended tunnel junctions and superconducting bridges for bolometer applications

Suspended NbN bridges and Nb/Al-AlOx/Nb trilayer tunnel junctions are well suited for bolometric detection of THz radiation.

Advantages include:

  • application-specific process flow
  • wafer-scale process
  • UV and E-beam capabilities
  • in-house device characterization
  • production scale-up capabilities
  • large detector arrays suitable for cryo-multiplexing
  • flexibility in a microfabrication process to meet customer demands
  • research, development and small scale production
  • in-house design, fabrication and testing capabilities
  • experience in building integrated end-user cyrogenic systems