Regensburg 2004 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 13: Messger
äte, Kryotechnik
TT 13.3: Vortrag
Dienstag, 9. März 2004, 16:30–16:45, H20
Nano-scaled superconducting meanders as single-photon detectors — •Andreas Engel1, Alexei Semenov1, Heinz-Wilhelm Hübers1, Konstantin Il’in2, and Michael Siegel2 — 1Deutsches Zentrum für Luft- und Raumfahrt, Rutherfordstr. 2, 12489 Berlin — 2Institut für Mikro- und Nanoelektronische Systeme, Universität Karlsruhe, Hertzstr. 16, 76187 Karlsruhe
There is great need for sensitive, fast, and energy-dispersive photon detectors in such diverse areas as far-infrared astronomy or x-ray spectroscopy. Nano-scaled superconducting meanders biased with a direct current slightly less than the critical current Ic(T) are promising candidates to close some of the gaps. Depending on the desired application and spectral range the thin (down to a few nm) and narrow (of the order of 100 nm or less) superconducting strips have to be fabricated from superconducting materials with varying critical temperature and thus varying energy gap Δ. An absorbed photon creates a hot spot with a normal conducting core. The bias current is expelled from the normal conducting core thereby increasing the current density in the side-walks until eventually the critical current density is exceeded. Information about the photon’s energy is contained in the height and duration of the resulting voltage transient.
We will present the latest theoretical models we use to describe experimental results and discuss some aspects with regard to detector performance. Examples are geometrical effects and dark count rates caused by superconducting fluctuations.