Berlin 2015 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 6: Superconductivity: Cryodetectors
TT 6.6: Vortrag
Montag, 16. März 2015, 10:45–11:00, H 2053
Nanofabrication of coulomb blockade thermometers — •Matthias Meschke1, Ossi M Hahtela2, Anna V Feshchenko1, Antti Kemppinen2, Martti Heinonen2, Antti Manninen2, and Jukka P Pekola1 — 1Aalto University, Espoo, Finland — 2Centre for Metrology and Accreditation (MIKES), Espoo, Finland
Coulomb blockade thermometry (CBT) is one example of a practical primary thermometer that relates temperature directly to Boltzmann's constant (kB) via a voltage measurement. Such primary methods are required for the realization of a proposed new international temperature scale that relates to thermodynamic temperature via an exact definition of kB.
Using cutting-edge electron beam lithography, we demonstrate the fabrication of arrays of small enough structures (30 nm x 30 nm) combined with extreme homogeneity (5%) widening the useful temperature range of precise CBT to higher temperatures up to about 40 K. We present a characterization of the remaining fabrication inhomogeneities as a part of the uncertainty budget of CBT that is one prerequisite for CBT measurements satisfying metrological standards. An improved accuracy of CBT sensors at elevated temperatures directly enhances the performance at lower temperatures via the improved homogeneity and the possibility to operate CBT in a stronger CB regime with enhanced signal magnitude.
Finally, we describe an experimental comparison of CBT, consisting of arrays of many (about 1000) tunnel junctions to thermometry realized using only a single tunnel junction.