J. Phys. IV France 12 (2002) Pr3-129
New developments in textured and epitaxial NbN superconducting layers for ultimate sensors and RSFQ digital circuitsJ.-C. Villégier1, N. Hadacek1, C. Jorel1, J.-L. Thomassin1, V. Bouchiat2, M. Faucher2, P. Febvre1, A. Rousy3 and G. Lamura4
1 CEA Grenoble, SPSMS/LCP, 38054 Grenoble cedex 9, France
2 CRTBT, CNRS, BP. 166, 38042 Grenoble cedex 9, France
3 LAHC, Université de Savoie, 73376 La Bourget du Lac cedex, France
4 LPS-ESPCI, 75231 Paris, France
Nitride superconductors and specially niobium nitride are key materials for developing high performance optoelectronic and digital circuits. We are presenting a way to achieve such high frequency devices on R-plane sapphire or MgO substrates. Deposition of thin and flat NbN films with Te above 10 K, low and reproducible penetration depth ( L 250 nm) and surface resistance (Rs) values up to I THz, is required and obtained by sputtering on a substrate heated in the 300-600 °C range. Simple sub-micrometer size HEB bridge structures where patterned even in a very thin (2-5 nm thick) NbN layers offering relaxation times below 30 ps. It is then possible to achieve fast optoelectronic data links and sensors on-chip with high clock frequency NbN RSFQ digital circuits.
© EDP Sciences 2002