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Quantum and superconducting sensing

VTT combines physics, electronics and nanofabrication expertise to better understand new phenomena in nanoscale structures and to find innovative, new solutions. Our main areas of competence include superconducting electronics and sensors, their readout electronics, and the applications of Josephson junction devices and circuits, supported by expertise in device fabrication and characterisation.

Low temperature quantum devices are used when ultimate performance is required, as is often the case with security and with medical and space applications. Recent areas of R&D concentration include MEG and low-field MRI imaging, THz applications and multiplexing of transition edge sensors with SQUID amplifiers.

Suspended tunnel junctions and superconducting bridges for bolometer applications

  • Well-established microfabrication process involving plasma etch-released superconducting structures on wafer scale
  • Multi-layer projection and contact lithography
  • Superconductors Nb and NbN, as well as the use of novel insulator materials and the integration of various resistive materials, including Mo (Tc ~ 0.9 K), TiW (Tc < 50 mK), etc.

A Nb/Al-AlOx/Nb trilayer structure provides a robust technology for Josephson junction-based devices and circuits.

Features include:

  • I-line projection lithography with minimum junction size below 2 μm
  • CMP planarized insulators for excellent step coverage
  • The possible use of different insulator materials
  • Nb Tc above 9 Kelvin
  • Resistor material Mo (Tc ≈ 0.9 K) or TiW (Tc < 50 mK)

THz imaging with superconducting bolometer

VTT has developed a compact video-rated THz scanner for security applications, based on superconducting hot-spot bolometers and a patented room temperature readout technique.

Nanothermoacoustics

AC current within suspended metal nanowires generates sound by heating the surrounding air. Using a simple and low-cost microfabrication process, nanothermoacoustics can be used efficiently, especially in ultrasonic applications.

Printed electric coding

VTT has developed a non-contact near-field readout technique for printed electric codes. These codes are invisible, inexpensive, low-cost and reliable. The reader that we have developed is integrated on a single ASIC, and is suitable for a wide variety of applications ranging from security and product authentication to games and toys.

Eliminating MEMS readout noise with sensor biasing

Because of the impedance mismatch and 1/f noise of integrated electronics, noise contribution of readout amplifier often dominates the MEMS sensor resolution. But by biasing the sensor to the pull-in point (X = 0.33 D0), the noise contribution of CMOS amplifier can be fully eliminated.