Study of superconductor-insulator-normal-insulator-superconductor (SINIS) junctions

In this paper we describe the fabrication and characterization of superconductor-insulator-normal (SIN) junctions and of superconductor-insulator-normal-insulator-superconductor (SINIS) double junctions (that is, two adjacent SIN junctions with a common normal electrode). The fabrication process is based on a thin film sandwich made by Nb/AlOx/Cu or by Al/AlOx/Cu. The interest in these junctions relies on the possibility to use them for refrigerating electrons in a metal.