Your Search Results

Use this resource - and many more! - in your textbook!

AcademicPub holds over eight million pieces of educational content for you to mix-and-match your way.

Experience the freedom of customizing your course pack with AcademicPub!
Not an educator but still interested in using this content? No problem! Visit our provider's page to contact the publisher and get permission directly.

High quality Ta/PbBi tunnel junctions for 85-110 GHz SIS mixer experiments

By: Raisanen, A.; Prober, D.; Track, E.; Face, D.; Cui, G.-J.; Richards, P.; Crete, D.;

1987 / IEEE


This item was taken from the IEEE Periodical ' High quality Ta/PbBi tunnel junctions for 85-110 GHz SIS mixer experiments ' We report on the fabrication of small area (1-6 �m2), high critical current density (103-104A/cm2) Ta/Ta oxide/ Pb0.9Bi0.1SIS tunnel junctions and six junction series arrays designed for use as broadband SIS quasiparticle mixers as 85-110 GHz. These junctions have small subgap leakage currents (1 to 5%), and a ""sharp"" current rise of width �V <30-50 �V at the sum gap voltage. An RF filter is fabricated on the substrate along with the junctions. The impedance of this filter combined with the junction capacitance is designed to provide a broadband RF match to the mixer over the entire frequency range. A sliding backshort is the only mechanical tuning element. The single junctions as well as arrays are fabricated with a window geometry on fused quartz substrates. The fused quartz substrates require the deposition of a thin amorphous Ge layer which is conducting as room temperature to avoid charging effects during the ion-beam processing steps. Preliminary measurements at 85- 100 GHz show a relatively low gain (-6.9 dB) compared to the performance expected for junctions of this quality. Model calculations suggest that the low gain arises from errors in the implementation of the RF filter design; this can be improved in future work.