PREPARATION OF SMALL-AREA AL ALOX/AL TUNNEL-JUNCTIONS IN A SELF-ALIGNED IN-LINE TECHNOLOGY AND OBSERVATION OF THE COULOMB-BLOCKADE/

We have demonstrated the suitability of a self-aligned in-line (SAIL) technique for the preparation of ultra-small high-ohmic tunnel junctio ns as required for the investigation of single-charge tunneling phenom ena. The Coulomb blockade his been observed at 14mK by means of a seri es array of five Al/AlO(x)/Al tunnel junctions operated in the normal- conducting state. We have applied this conception to the fabrication o f single junctions in a Nb/NbO(x)/PbAuIn system as well. At 4.2K these samples show the typical I-V behaviour of Josephson tunnel junctions as expected. The compatibility of this process with several thin film deposition techniques, evaporation as well as sputtering, extremely sm all parasitic capacitances and excellent integrability promise interes ting applications in both single-charge electronics and Josephson phys ics.