HIGH-QUALITY NB-ALOXNB JUNCTIONS FOR MICROWAVE RECEIVERS AND SFQ LOGIC DEVICE

The high quality Nb-AlO(x)-Nb tunnel junctions have been successfully used 1-4 for the creation of the low noise SIS mixer and elaboration of the SQUIDs and SFQ logic devices. In this work the specific capacitance of high quality (V(m) > 50 mV) Nb-AlO(x)-Nb tunnel junctions has been determined by the following methods: i) the measurement of Zero Field Step resonances in specially prepared long Josephson junctions; ii) the definition of the resonant voltages in two-junctions interferometers based on Nb-AlO(x)-Nb junctions. The results obtained by these methods were compared with each other and with the figures calculated from the measurements of tunnel barrier parameters. The application of the developed technological procedure for the fabrication of the SFQ logic devices have been discussed.