All refractory light-sensitive superconductive tunnel junctions

A procedure for fabricating all refractory superconducting tunnel junctions with a photoconducting barrier is reported. The process is based on the deposition of a multilayer structure without breaking the vacuum. Both symmetrical Nb/Al-CdSCAlCy-Al/Nb and asymmetrical Nb/Al-CdSCAlO-4/Nb junctions have been fabricated. The photoconducting behavior of the CdS film gives the possibility of modifying the tunnel barrier transparency during the experiments by a suitable optical input. Results of experimental investigations performed on samples having a barrier thickness in the range 7-50 nm are discussed. ©Société Italiana di Fisica.