Regensburg 2010 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 9: SC: Poster Session

TT 9.54: Poster

Montag, 22. März 2010, 14:00–18:00, Poster A

Spatially Resolved Photoresponse of NbN Nanowires — •Philipp Jung¹, Alexander Lukashenko¹, Alexander P. Zhuravel², Stefan Wuensch¹, Matthias Hofherr¹, Konstantin Ilin¹, Michael Siegel¹, and Alexey V. Ustinov¹ — ¹Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany — ²B. Verkin Institute for Low Temperature Physics & Engineering, Kharkov Ukraine

We are investigating optical response of superconducting nanowires patterned from thin NbN films deposited on sapphire and Si substrates. These structures are often used for radiation detectors like single-photon detectors and hot-electron bolometer mixers. In our experiments, we precisely position a focused laser beam on the detector to correlate the response to a local excitation. Scanning the laser spot over the sample surface allows us to obtain response maps of the investigated wires.

We have found spatially localized weak areas in case of NbN films on sapphire substrates, which can be attributed to grain boundaries with suppressed superconducting properties. In opposite, the strongest response of NbN bridges on Si substrates was obtained at the edges of bridges. We are going to present and analyze the dependence of response of NbN thin film bridges on light intensity and operation temperature.