SUPERCONDUCTIVE ELEMENT

PURPOSE:To make fine and speed up the titled element utilizing Josephson effect by a method wherein this element is provided with a barrier layer made of an insulator whose composition has been specified, having apertures rectangularly intersecting with each other between the upper and lower electrodes, and the aperture area of these apertures is restricted. CONSTITUTION:An Nb film of about 300nm thickness is adhered on a sapphire substrate, and etched into the lower electrode 1, and the upper electrode 6 of Pb-5wt% In alloy of about 500nm thickness is provided via barrier layer consisting of insulation films 2 and 4 having thereon the linear apertures 3 and 5 rectangularly intersecting with each other; thus, making the whole as the titled element. In this construction, the thickness of the barrier layer is set to 2-4nm, and a material selected out of SiO2, Al2O3, MgO, MgF2, ZnO, an Si nitride, BeO, or Cr oxide or Si, Ge is used for the insulation films 2 and 4. Further, the area of the intersecting apertures 3 and 5 is restricted to 4mum or less.