Dresden 2014 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 30: Superconductivity - Poster Session
TT 30.62: Poster
Monday, March 31, 2014, 15:00–19:00, P2
Ultra-thin TaN films on different substrates for superconducting detectors — •Ilya Charaev, Konstantin Ilin, and Michael Siegel — Institute of Micro- and Nanoelectronic Systems, Karlsruhe Institute of Technology, Hertzstrasse 16, Karlsruhe, Germany
Superconductors widely used for development of detectors with ultimate sensitivity. For example, Tantalum Nitride (TaN) is a promising material for superconducting nanowire single-photon detector (SNSPD) in a wide spectral range. We report on a study of superconducting, normal state and thermal properties of ultra-thin TaN films for SNSPD. The films with a thickness of 5.5 nm were deposited by reactive magnetron sputtering in an Ar+N2 atmosphere on different substrates like Sapphire, Si, MgO and Si with AlN buffer layer. While the critical temperatures Tc and the critical current density jc (4.2 K) of TaN films on sapphire and MgO substrates have been found almost identically (about 9.3 K and 4 MA/cm2 correspondingly) the Tc values of the films on Si substrate were much lower (4.76 K). Using a buffer layer of AlN the Tc of TaN on Si (important for THz applications) has been increased up to 7 K. Thermal coupling (estimated from the hysteresis current density) between TaN films and MgO and Sapphire substrates has been found alike while on Si substrates with AlN buffer layer the coupling was much weaker. A detailed analysis of the influence of substrate material on properties of TaN films will be presented and the potential of TaN films for different applications will be discussed.