Photoresponse experiments on NbN proximized nanostructures

Abstract

Among superconducting materials used in developing high performance nanowire detectors, NbN demonstrated to have unique characteristics in terms of fast response time, quantum efficiency and photon-number resolving capability. We investigated the role of proximity effect on superconducting NbN thin films covered by a weak ferromagnetic NiCu thin layer. Hetero-structures NbN/NiCu have been deposited by DC magnetron sputtering on MgO substrates without any heating. Characterization in terms of morphological, transport, and ultra-fast optical properties has been done. Superconducting nanowires with meander-type geometries (48 micron lengths and <500 nm widths) have been designed and fabricated. Preliminary results concerning their photoresponse to 1550nm laser irradiation are presented. © © 2010 IOP Publishing Ltd.