59 citations · 134 across the 10 of their papers we have counts for
9 papers · 1 filter
Efficient electronic cooling above 2 K by niobium-based superconducting tunnel junctions
J. Hätinen, A. Ronzani, R. P. Loreto +15
Replacing the bulky cryoliquid-based cooling stages of cryoenabled instruments by chip-scale refrigeration is envisioned to disruptively reduce the system size similar to microproc…
Effect of ion irradiation on superconducting thin films
Katja Kohopää, Alberto Ronzani, Robab Najafi Jabdaraghi +8
We demonstrate ion irradiation by argon or gallium as a wafer-scale post-processing method to increase disorder in superconducting thin films. We study several widely used supercon…
Cascaded superconducting junction refrigerators: optimization and performance limits
A. Kemppinen, A. Ronzani, E. Mykkänen +3
We demonstrate highly transparent silicon-vanadium and silicon-aluminum tunnel junctions with relatively low sub-gap leakage current and discuss how a trade-off typically encounter…
Flux-driven Josephson parametric amplifier for sub-GHz frequencies fabricated with side-wall passivated spacer junction technology
Slawomir Simbierowicz, Visa Vesterinen, Leif Grönberg +3
We present experimental results on a Josephson parametric amplifier tailored for readout of ultra-sensitive thermal microwave detectors. In particular, we discuss the impact of fab…
Superconducting MoSi nanowires
J. S. Lehtinen, A. Kemppinen, E. Mykkänen +2
We have fabricated disordered superconducting nanowires of molybdenium silicide. A molybdenium nanowire is first deposited on top of silicon, and the alloy is formed by rapid therm…
Side-wall spacer passivated sub-um Josephson junction fabrication process
Leif Grönberg, Mikko Kiviranta, Visa Vesterinen +5
We present a structure and a fabrication method for superconducting tunnel junctions down to the dimensions of 200 nm using i-line UV lithography. The key element is a side-wall-pa…