Experimental investigation of double-barrier SINIS (superconductor-insulator-normal-insulator-superconductor) structures

Double-barrier Nb/AlOx /Al/AlOx /Nb devices were fabricated and investigated in direct-current and alternating-current (ac) electromagnetic fields. The occurrence of current singularities and of the ac Josephson effect at T = 4.2 K are demonstrated. In a three-terminal configuration, a transistor-like behaviour of the structure is also observed.