Berlin 2012 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
TT: Fachverband Tiefe Temperaturen
TT 36: Superconductivity: Cryodetectors
TT 36.4: Vortrag
Donnerstag, 29. März 2012, 10:15–10:30, H 2053
Influence of geometry on the critical current of superconducting nanowire single-photon detectors — •Dagmar Henrich1, Patrick Reichensperger1, Matthias Hofherr1, Konstantin Il'in1, Michael Siegel1, Alexei Semenov2, Heinz-Wilhelm Hübers2,3, and Denis Vodolazov4 — 1IMS, Karlsruhe Institut für Technologie, Karlsruhe, Germany — 2DLR, Berlin, Germany — 3IOAP, Technische Universität Berlin, Berlin, Germany — 4Nizhni Novgorod State University, Nizhni Novgorod, Russia
Superconducting Nanowire Single Photon Detectors (SNSPD) are made from thin superconducting films which are patterned into very narrow meander shaped lines. The current density distribution inside the nanowire, predicted by theory, shows an accumulation at the inner edges of such turns, which limits the total device critical current. Since the sensitivity of the SNSPDs as well as the spectral detection efficiency are strongly dependent on the factor of the local bias current to the critical current, the designs must be optimized to homogenize the current distribution. We experimentally investigate the influence of the angle and radius of curves on the critical current of nanowires. The samples are 300 nm wide nanowires made from ultra-thin NbN films deposited by DC reactive magnetron sputtering on 750°C heated sapphire substrates. Based on the results, we propose a design of an optimized detector layout for SNSPDs with homogeneous local detection efficiency.