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TT: Fachverband Tiefe Temperaturen
TT 60: SC \& MLT: Cryodetectors
TT 60.1: Talk
Friday, March 18, 2011, 10:30–10:45, HSZ 301
Ultra-thin TaN films for infrared Superconducting Nanowire Single-Photon Detectors — •Konstantin Ilin1, Dagmar Rall1,4, Matthias Hofherr1, Michael Siegel1,5, Alexei Semenov2, Heinz-Wilhelm Hübers2, Andreas Engel3, Kevin Inderbitzin3, Adrian Aeschbacher3, and Andreas Schilling3 — 1IMS, Karlsuher Institut für Technologie, Karlsruhe, Deutschland — 2DLR Institut für Planetenforschung, Berlin, Deutschland — 3Physik-Institut der Universität Zürich, Zürich, Schweiz — 4LTI, KIT, Karlsruhe, Deutschland — 5DFG CFN, Karlsruhe, Deutschland
The quest for the development of superconducting nanowire single-photon detectors (SNSPD) with higher intrinsic detection efficiency in a wider spectral range stimulates the study of ultra-thin films of different superconducting materials. Tantalum nitride (TaN) is considered as a promising candidate for the development of SNSPDs for infra-red radiation. Thin superconducting TaN films were deposited by reactive magnetron sputtering from a pure Ta target in a gas mixture of Ar and N2. The films were deposited on sapphire substrates heated to about 550 C. The transition temperature Tc of the thickest films (15 nm) was about 9.6 K. It decreased with the thickness remaining larger than 7 K for films with a thickness of 4 nm. SNSPDs made from TaN films have a critical current density of a few MA/cm2 at 4.2K and Tc only slightly less than Tc of non-patterned films. Superconducting and normal state properties of micrometer and sub-micrometer sized TaN structures will be discussed in details. The single-photon response of TaN SNSPDs will be presented for the first time.