Berlin 2008 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 5: Superconductivity - Cryodetectors

TT 5.5: Talk

Monday, February 25, 2008, 12:45–13:00, H 3010

Performance enhancement of a superconducting nanowire single-photon detector at low temperatures — •Alexej Semenov¹, Phillip Haas¹, Heinz-Wilhelm Huebers¹, Konstantin Il’in², Michael Siegel², and Rudolf Herrmann³ — ¹DLR Institute of Planetary Research, 12489 Berlin, Germany — ²Institute of Micro- and Nano-Electronic Systems, University of Karlsruhe, 76187 Karlsruhe, Germany — ³Institute of Appplied Photonics, 12489 Berlin, Germany

We report on the low-temperature operation of superconducting nanowire single-photon detectors. The nanowires were patterned from a 5-nm thick B1 niobium nitride film to form a 100-nm wide meander-line. NbN films had a quality assuring the Ginsburg-Landau deparing current in the detector structures at all temperature below the transition temperature. At 6 K operation, a resolution of 0.55 eV was measured in the wavelength range from 1000 nm to 1500 nm along with the quantum efficiency of a few percent for ultra-violet and visible-light quanta. Decreasing operation temperature to 1.4 K with a ³He sorption refrigerator combined with a mechanical pulse-tube cooler, we found a threefold increase in the quantum efficiency and an almost 50% improvement of the energy resolution. The quantum efficiency at low temperatures was limited to the absorbance of the structure. Although the energy resolution and single-photon detection ability is better explained by an unbinding of vortex-antivortex pairs, the observed temperature enhancement of the detector perfermance is most likely due to the non-homogeneity of the meander-line.